A compact collimator for light-emitting diode (LED) source is designed. The collimator is a catadioptric rotational system. The refraction part is used to collimate the rays with small view angle, and the reflection part is used to collimate the rays with large view angle. The design results are verified by optical simulation software TracePro. The results show that the divergence angle can be reduced to about 4° from 70° by the collimator with the optical efficiency of 85%. The height and diameter of the system are 7.65 mm and 8.73 mm, respectively. The optimal separation angle range is 41°～45°, and the optimal proportion factor range of refraction angle is 0.4～0.5.