As the key component of Active Phased Array Radar, the phase shift precision of T/R module has the important role on the performance of radar. A research on K-band High frequency T/R module is made in this paper, in the case which the phase shift precision can not meet the index request with the single numerical control phase shift, the method of combining the single numerical control phase shift with the little-bit phase shift is presented ,which greatly improves the phase shift precision. The measure result shows that the RMS is below 2.3 degrees, while the phased shift precision of all the phase shift state is within 8 degrees, which greatly improves the phased shift precision of T/R module, ensuring the sweep precision of the system.