diff --git a/brainpy/_src/math/tests/taichi_random_time_test.py b/brainpy/_src/math/tests/taichi_random_time_test.py
index 45d836e9c..4d0cddf9b 100644
--- a/brainpy/_src/math/tests/taichi_random_time_test.py
+++ b/brainpy/_src/math/tests/taichi_random_time_test.py
@@ -34,23 +34,6 @@ def test_taichi_xorwow(seed: ti.types.ndarray(ndim=1, dtype=ti.u32),
         seeds1, seeds2, result = taichi_xorwow(seeds1, seeds2)
         out[i] = result
         
-@ti.kernel
-def test_taichi_lfsr88_0(seed: ti.types.ndarray(ndim=1, dtype=ti.u32),
-                        out: ti.types.ndarray(ndim=1, dtype=ti.f32)):
-    s1, s2, s3, b = init_lfsr88_seeds_0(seed[0])
-    for i in range(out.shape[0]):
-        s1, s2, s3, b, result = taichi_lfsr88_0(s1, s2, s3, b)
-        out[i] = result
-    
-@ti.kernel
-def test_taichi_xorwow_0(seed: ti.types.ndarray(ndim=1, dtype=ti.u32),
-                        out: ti.types.ndarray(ndim=1, dtype=ti.f32)):
-    x, y, z, w, v, d = init_xorwow_seeds_0(seed[0])
-    # print(seeds1, seeds2)
-    for i in range(out.shape[0]):
-        x, y, z, w, v, d, result = taichi_xorwow_0(x, y, z, w, v, d)
-        out[i] = result
-
 n = 100000000
 seed = jnp.array([1234, ], dtype=jnp.uint32)
 
@@ -60,12 +43,6 @@ def test_taichi_xorwow_0(seed: ti.types.ndarray(ndim=1, dtype=ti.u32),
 prim_xorwow = bm.XLACustomOp(cpu_kernel=test_taichi_xorwow,
                             gpu_kernel=test_taichi_xorwow)
 
-prim_lfsr88_0 = bm.XLACustomOp(cpu_kernel=test_taichi_lfsr88_0,
-                               gpu_kernel=test_taichi_lfsr88_0)
-  
-prim_xorwow_0 = bm.XLACustomOp(cpu_kernel=test_taichi_xorwow_0,
-                            gpu_kernel=test_taichi_xorwow_0)
-
 out = jax.block_until_ready(prim_lfsr88(seed, outs=[jax.ShapeDtypeStruct((n,), jnp.float32)]))
 time0 = time.time()
 out = jax.block_until_ready(prim_lfsr88(seed, outs=[jax.ShapeDtypeStruct((n,), jnp.float32)]))
@@ -76,17 +53,6 @@ def test_taichi_xorwow_0(seed: ti.types.ndarray(ndim=1, dtype=ti.u32),
 out = jax.block_until_ready(prim_xorwow(seed, outs=[jax.ShapeDtypeStruct((n,), jnp.float32)]))
 time3 = time.time()
 
-out = jax.block_until_ready(prim_lfsr88_0(seed, outs=[jax.ShapeDtypeStruct((n,), jnp.float32)]))
-time4 = time.time()
-out = jax.block_until_ready(prim_lfsr88_0(seed, outs=[jax.ShapeDtypeStruct((n,), jnp.float32)]))
-time5 = time.time()
-
-out = jax.block_until_ready(prim_xorwow_0(seed, outs=[jax.ShapeDtypeStruct((n,), jnp.float32)]))
-time6 = time.time()
-out = jax.block_until_ready(prim_xorwow_0(seed, outs=[jax.ShapeDtypeStruct((n,), jnp.float32)]))
-time7 = time.time()
 
 print('lfsr88: ', time1 - time0)
 print('xorwow: ', time3 - time2)
-print('lfsr88_0: ', time5 - time4)
-print('xorwow_0: ', time7 - time6)