diff --git a/src/public/py_str.c b/src/public/py_str.c
index d53f20d7..98e09512 100644
--- a/src/public/py_str.c
+++ b/src/public/py_str.c
@@ -436,6 +436,28 @@ static bool _py_str__rjust(int argc, py_Ref argv) {
     return _py_str__widthjust_impl(false, argc, argv);
 }
 
+static bool _py_str__find(int argc, py_Ref argv) {
+    if(argc > 3) return TypeError("find() takes at most 3 arguments");
+    int start = 0;
+    if(argc == 3) {
+        PY_CHECK_ARG_TYPE(2, tp_int);
+        start = py_toint(py_arg(2));
+    }
+    c11_string* self = py_touserdata(&argv[0]);
+    PY_CHECK_ARG_TYPE(1, tp_str);
+    c11_string* sub = py_touserdata(&argv[1]);
+    int res = c11_sv__index2(c11_string__sv(self), c11_string__sv(sub), start);
+    py_newint(py_retval(), res);
+    return true;
+}
+
+static bool _py_str__index(int argc, py_Ref argv) {
+    bool ok = _py_str__find(argc, argv);
+    if(!ok) return false;
+    if(py_toint(py_retval()) == -1) return ValueError("substring not found");
+    return true;
+}
+
 py_Type pk_str__register() {
     pk_VM* vm = pk_current_vm;
     py_Type type = pk_VM__new_type(vm, "str", tp_object, NULL, false);
@@ -474,6 +496,8 @@ py_Type pk_str__register() {
     py_bindmethod(tp_str, "zfill", _py_str__zfill);
     py_bindmethod(tp_str, "ljust", _py_str__ljust);
     py_bindmethod(tp_str, "rjust", _py_str__rjust);
+    py_bindmethod(tp_str, "find", _py_str__find);
+    py_bindmethod(tp_str, "index", _py_str__index);
     return type;
 }
 
diff --git a/tests/04_str.py b/tests/04_str.py
index de293689..d092e7bc 100644
--- a/tests/04_str.py
+++ b/tests/04_str.py
@@ -108,6 +108,23 @@ assert str(num) == '6'
 测试 = "test"
 assert 测试 == "test"
 
+a = 'abcd'
+assert list(a) == ['a', 'b', 'c', 'd']
+a = '测试'
+assert list(a) == ['测', '试']
+a = 'a测b试c'
+assert list(a) == ['a', '测', 'b', '试', 'c']
+a = 'a测b试'
+assert list(a) == ['a', '测', 'b', '试']
+a = '测b试c'
+assert list(a) == ['测', 'b', '试', 'c']
+a = '测b'
+assert list(a) == ['测', 'b']
+a = 'b'
+assert list(a) == ['b']
+a = '测'
+assert list(a) == ['测']
+
 # 3rd slice
 a = "Hello, World!"
 assert a[::-1] == "!dlroW ,olleH"
@@ -126,6 +143,18 @@ assert '\x30\x31\x32' == '012'
 assert '\b\b\b' == '\x08\x08\x08'
 assert repr('\x1f\x1e\x1f') == '\'\\x1f\\x1e\\x1f\''
 
+a = '123'
+assert a.index('2') == 1
+assert a.index('1') == 0
+assert a.index('3') == 2
+assert a.index('23') == 1
+
+assert a.index('2', 1) == 1
+assert a.index('1', 0) == 0
+
+assert a.find('1') == 0
+assert a.find('1', 1) == -1
+
 b = list("Hello, World!")
 assert b == ['H', 'e', 'l', 'l', 'o', ',', ' ', 'W', 'o', 'r', 'l', 'd', '!']
 assert b[::-1] == ['!', 'd', 'l', 'r', 'o', 'W', ' ', ',', 'o', 'l', 'l', 'e', 'H']
@@ -146,34 +175,6 @@ assert hex(256) == '0x100'
 assert hex(257) == '0x101'
 assert hex(17) == '0x11'
 
-a = '123'
-assert a.index('2') == 1
-assert a.index('1') == 0
-assert a.index('3') == 2
-
-assert a.index('2', 1) == 1
-assert a.index('1', 0) == 0
-
-assert a.find('1') == 0
-assert a.find('1', 1) == -1
-
-a = 'abcd'
-assert list(a) == ['a', 'b', 'c', 'd']
-a = '测试'
-assert list(a) == ['测', '试']
-a = 'a测b试c'
-assert list(a) == ['a', '测', 'b', '试', 'c']
-a = 'a测b试'
-assert list(a) == ['a', '测', 'b', '试']
-a = '测b试c'
-assert list(a) == ['测', 'b', '试', 'c']
-a = '测b'
-assert list(a) == ['测', 'b']
-a = 'b'
-assert list(a) == ['b']
-a = '测'
-assert list(a) == ['测']
-
 def test(*seq):
     return s1.join(seq)
 assert test("r", "u", "n", "o", "o", "b") == "r-u-n-o-o-b"