diff --git a/core/src/lib.rs b/core/src/lib.rs
index 53700bf..813598e 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -2,8 +2,8 @@
 
 pub mod ai;
 pub mod board;
-pub mod rules;
-pub mod record;
 pub mod llm;
 pub mod network;
+pub mod record;
+pub mod rules;
 pub mod types;
diff --git a/core/src/llm.rs b/core/src/llm.rs
new file mode 100644
index 0000000..9b5ac05
--- /dev/null
+++ b/core/src/llm.rs
@@ -0,0 +1,129 @@
+use crate::ai::AiEngine;
+use crate::board::Board;
+use crate::types::{CellState, Color, Position};
+
+/// 大模型 AI — 通过 HTTP API 调用
+pub struct LlmAi {
+    endpoint: String,
+    api_key: String,
+    model: String,
+}
+
+impl LlmAi {
+    pub fn new(endpoint: &str, api_key: &str, model: &str) -> Self {
+        Self {
+            endpoint: endpoint.to_string(),
+            api_key: api_key.to_string(),
+            model: model.to_string(),
+        }
+    }
+
+    /// 将棋盘序列化为 prompt
+    pub fn board_to_prompt(board: &Board, color: Color) -> String {
+        let mut s = String::from("你是一位五子棋高手。当前棋盘状态(0=空,1=黑,2=白):\n");
+        for x in 0..board.size {
+            for y in 0..board.size {
+                let ch = match board.get(Position::new(x, y)) {
+                    CellState::Empty => '0',
+                    CellState::Occupied(Color::Black) => '1',
+                    CellState::Occupied(Color::White) => '2',
+                };
+                s.push(ch);
+                s.push(' ');
+            }
+            s.push('\n');
+        }
+        let color_str = match color {
+            Color::Black => "黑棋(1)",
+            Color::White => "白棋(2)",
+        };
+        s.push_str(&format!(
+            "\n你是{}, 请返回最佳落子坐标 (格式: x,y)",
+            color_str
+        ));
+        s
+    }
+
+    /// 解析 LLM 响应中的坐标
+    pub fn parse_response(response: &str) -> Option<Position> {
+        let bytes = response.as_bytes();
+        for (i, &b) in bytes.iter().enumerate() {
+            if b != b',' {
+                continue;
+            }
+            // 从逗号向前找数字起始
+            let x_start = (0..i)
+                .rev()
+                .take_while(|&j| bytes[j].is_ascii_digit())
+                .last()
+                .unwrap_or(i);
+            if x_start == i {
+                continue;
+            }
+            // 从逗号向后跳过空格找数字起始
+            let y_start = (i + 1..bytes.len()).find(|&j| bytes[j].is_ascii_digit())?;
+            // 从 y_start 向后找数字结束
+            let y_end = (y_start + 1..bytes.len())
+                .find(|&j| !bytes[j].is_ascii_digit())
+                .unwrap_or(bytes.len());
+
+            let x_str = &response[x_start..i];
+            let y_str = &response[y_start..y_end];
+            if let (Ok(x), Ok(y)) = (x_str.parse::<usize>(), y_str.parse::<usize>()) {
+                return Some(Position::new(x, y));
+            }
+        }
+        None
+    }
+}
+
+impl AiEngine for LlmAi {
+    fn best_move(&self, board: &Board, color: Color) -> Option<Position> {
+        let prompt = Self::board_to_prompt(board, color);
+        let client = reqwest::blocking::Client::new();
+        let body = serde_json::json!({
+            "model": self.model,
+            "messages": [
+                {"role": "user", "content": prompt}
+            ],
+            "max_tokens": 50,
+            "temperature": 0.3
+        });
+
+        let resp = client
+            .post(&self.endpoint)
+            .header("Authorization", format!("Bearer {}", self.api_key))
+            .header("Content-Type", "application/json")
+            .json(&body)
+            .send()
+            .ok()?;
+
+        let json: serde_json::Value = resp.json().ok()?;
+        let content = json["choices"][0]["message"]["content"].as_str()?;
+        Self::parse_response(content)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_coordinate() {
+        assert_eq!(LlmAi::parse_response("7,8"), Some(Position::new(7, 8)));
+        assert_eq!(LlmAi::parse_response("(7, 8)"), Some(Position::new(7, 8)));
+        assert_eq!(
+            LlmAi::parse_response("坐标是 10,5"),
+            Some(Position::new(10, 5))
+        );
+        assert_eq!(LlmAi::parse_response("no coordinate"), None);
+    }
+
+    #[test]
+    fn test_board_to_prompt() {
+        let board = Board::new(15);
+        let prompt = LlmAi::board_to_prompt(&board, Color::Black);
+        assert!(prompt.contains("黑棋(1)"));
+        assert!(prompt.contains("0 0 0"));
+    }
+}