diff --git a/src/captcha/captcha.service.ts b/src/captcha/captcha.service.ts
index c7a8149..5b00d88 100644
--- a/src/captcha/captcha.service.ts
+++ b/src/captcha/captcha.service.ts
@@ -13,9 +13,9 @@ export class CaptchaService {
   generate(): GeneratedCaptcha {
     const captcha = svgCaptcha.create({
       size: 5,
-      ignoreChars: "0oO1ilI",
-      noise: 3,
-      color: true,
+      ignoreChars: "abcdefghijklmnopqrstuvwxyzACDEFGHIJKLMNOPQRSTUVWXYZ",
+      noise: 1,
+      color: false,
       background: "#f8fafc",
       width: 160,
       height: 56,