diff --git a/backend/config.yaml b/backend/config.yaml
new file mode 100644
index 0000000..ab4607f
--- /dev/null
+++ b/backend/config.yaml
@@ -0,0 +1,37 @@
+# config.yaml — 默认配置
+app:
+  env: dev
+
+server:
+  host: "0.0.0.0"
+  port: 8080
+  read_timeout: 30
+  write_timeout: 30
+
+redis:
+  addr: "localhost:6379"
+  password: ""
+  db: 0
+
+ai:
+  stt:
+    provider: deepgram
+    endpoint: "wss://api.deepgram.com/v1/listen"
+  llm:
+    provider: openai
+    model: gpt-4o
+    endpoint: "https://api.openai.com/v1"
+    timeout: 10
+  tts:
+    provider: openai
+    voice: alloy
+    speed: 1.0
+    endpoint: "https://api.openai.com/v1"
+    timeout: 5
+
+storage:
+  driver: memory
+
+log:
+  level: info
+  format: console
diff --git a/backend/internal/config/config.go b/backend/internal/config/config.go
new file mode 100644
index 0000000..d8c252c
--- /dev/null
+++ b/backend/internal/config/config.go
@@ -0,0 +1,150 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/spf13/viper"
+)
+
+// Config 应用配置。
+type Config struct {
+	App     AppConfig     `mapstructure:"app"`
+	Server  ServerConfig  `mapstructure:"server"`
+	Redis   RedisConfig   `mapstructure:"redis"`
+	AI      AIConfig      `mapstructure:"ai"`
+	Storage StorageConfig `mapstructure:"storage"`
+	Log     LogConfig     `mapstructure:"log"`
+}
+
+type AppConfig struct {
+	Env     string `mapstructure:"env"`
+	Version string `mapstructure:"version"`
+}
+
+type ServerConfig struct {
+	Host         string `mapstructure:"host"`
+	Port         int    `mapstructure:"port"`
+	ReadTimeout  int    `mapstructure:"read_timeout"`
+	WriteTimeout int    `mapstructure:"write_timeout"`
+}
+
+// Addr 返回 host:port 地址。
+func (s ServerConfig) Addr() string {
+	return fmt.Sprintf("%s:%d", s.Host, s.Port)
+}
+
+type RedisConfig struct {
+	Addr     string `mapstructure:"addr"`
+	Password string `mapstructure:"password"`
+	DB       int    `mapstructure:"db"`
+}
+
+type AIConfig struct {
+	STT STTConfig `mapstructure:"stt"`
+	LLM LLMConfig `mapstructure:"llm"`
+	TTS TTSConfig `mapstructure:"tts"`
+}
+
+type STTConfig struct {
+	Provider string `mapstructure:"provider"`
+	APIKey   string `mapstructure:"api_key"`
+	Endpoint string `mapstructure:"endpoint"`
+}
+
+type LLMConfig struct {
+	Provider string `mapstructure:"provider"`
+	APIKey   string `mapstructure:"api_key"`
+	Model    string `mapstructure:"model"`
+	Endpoint string `mapstructure:"endpoint"`
+	Timeout  int    `mapstructure:"timeout"`
+}
+
+type TTSConfig struct {
+	Provider string  `mapstructure:"provider"`
+	APIKey   string  `mapstructure:"api_key"`
+	Voice    string  `mapstructure:"voice"`
+	Speed    float64 `mapstructure:"speed"`
+	Endpoint string  `mapstructure:"endpoint"`
+	Timeout  int     `mapstructure:"timeout"`
+}
+
+type StorageConfig struct {
+	Driver string `mapstructure:"driver"`
+	DSN    string `mapstructure:"dsn"`
+}
+
+type LogConfig struct {
+	Level  string `mapstructure:"level"`
+	Format string `mapstructure:"format"`
+}
+
+// Load 加载配置。优先级：环境变量 > config.{env}.yaml > config.yaml。
+func Load() (*Config, error) {
+	v := viper.New()
+	v.SetConfigName("config")
+	v.SetConfigType("yaml")
+	v.AddConfigPath(".")
+	v.AddConfigPath("./config")
+	v.AddConfigPath("./backend")
+
+	// 默认值
+	v.SetDefault("app.env", "dev")
+	v.SetDefault("server.host", "0.0.0.0")
+	v.SetDefault("server.port", 8080)
+	v.SetDefault("server.read_timeout", 30)
+	v.SetDefault("server.write_timeout", 30)
+	v.SetDefault("redis.addr", "localhost:6379")
+	v.SetDefault("redis.db", 0)
+	v.SetDefault("ai.stt.provider", "deepgram")
+	v.SetDefault("ai.stt.endpoint", "wss://api.deepgram.com/v1/listen")
+	v.SetDefault("ai.llm.provider", "openai")
+	v.SetDefault("ai.llm.model", "gpt-4o")
+	v.SetDefault("ai.llm.endpoint", "https://api.openai.com/v1")
+	v.SetDefault("ai.llm.timeout", 10)
+	v.SetDefault("ai.tts.provider", "openai")
+	v.SetDefault("ai.tts.voice", "alloy")
+	v.SetDefault("ai.tts.speed", 1.0)
+	v.SetDefault("ai.tts.endpoint", "https://api.openai.com/v1")
+	v.SetDefault("ai.tts.timeout", 5)
+	v.SetDefault("storage.driver", "memory")
+	v.SetDefault("log.level", "info")
+	v.SetDefault("log.format", "console")
+
+	// 读取基础配置文件
+	_ = v.ReadInConfig() // 文件不存在不报错
+
+	// 根据 APP_ENV 覆盖
+	env := os.Getenv("APP_ENV")
+	if env == "" {
+		env = v.GetString("app.env")
+	}
+	if env != "" {
+		v.SetConfigName("config." + env)
+		_ = v.MergeInConfig()
+	}
+
+	// 环境变量覆盖
+	v.SetEnvPrefix("CAMTALK")
+	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
+	v.AutomaticEnv()
+
+	var cfg Config
+	if err := v.Unmarshal(&cfg); err != nil {
+		return nil, fmt.Errorf("config unmarshal: %w", err)
+	}
+
+	// 填充默认值
+	if cfg.Server.Host == "" {
+		cfg.Server.Host = "0.0.0.0"
+	}
+	if cfg.Server.Port == 0 {
+		cfg.Server.Port = 8080
+	}
+	if cfg.App.Env == "" {
+		cfg.App.Env = "dev"
+	}
+
+	return &cfg, nil
+}