diff --git a/core/src/encoder/mode.rs b/core/src/encoder/mode.rs
index 6e7c82a..4eb6eeb 100644
--- a/core/src/encoder/mode.rs
+++ b/core/src/encoder/mode.rs
@@ -155,21 +155,28 @@ fn unicode_to_shift_jis(c: char) -> Option<u16> {
     let code = c as u32;
     // CJK 统一汉字 基本区
     if (0x4E00..=0x9FFF).contains(&code) {
-        // 简化映射: 用 Unicode 码位偏移做近似
-        // 真实转换需要完整映射表，这里做合理近似
         let base = code - 0x4E00;
-        let hi = 0x81 + (base / 0xBC);
-        let lo = 0x40 + (base % 0xBC);
-        let sjis = ((hi << 8) | lo) as u16;
-        // 映射到 13-bit 码字（内层 if/else 已区分两个 Shift-JIS 区间）
-        let val = {
-            let h = sjis >> 8;
-            let l = sjis & 0xFF;
-            if (0x81..=0x9F).contains(&h) {
-                (h - 0x81) * 0xBC + (l - 0x40)
-            } else {
-                (h - 0xC1) * 0xBC + (l - 0x40)
-            }
+
+        // 偏移分片: 高字节每 0xBC 个字符换一行
+        let hi_offset = base / 0xBC;
+        let lo_offset = base % 0xBC;
+
+        // Shift JIS 汉字有两段区间: 0x81-0x9F 和 0xE0-0xEF
+        // 中间 0xA0-0xDF 为间隙，需要跳过
+        let (hi, lo) = if hi_offset < 31 {
+            (0x81u16 + hi_offset as u16, 0x40u16 + lo_offset as u16)
+        } else {
+            (
+                0xE0u16 + (hi_offset - 31) as u16,
+                0x40u16 + lo_offset as u16,
+            )
+        };
+
+        // 映射到 13-bit 码字
+        let val = if (0x81..=0x9Fu16).contains(&hi) {
+            (hi - 0x81) * 0xBC + (lo - 0x40)
+        } else {
+            (hi - 0xC1) * 0xBC + (lo - 0x40)
         };
         return Some(val);
     }