Abstract: This paper presents a power combiner with high performance at W band. In order to reduce the return loss effectively, two isosceles triangle metal blocks are embedded in the narrow coupling wall and the waveports are drew forth by 90 degree mitered corners to meet the engineering application. First, the basic structural parameters are analysised by odd e ven modes, then the size is simulated and optimized by HFSS. Futher and an optimized combiner is fabricated and meas ured. The measured results show that the additional total insertion loss is less than 1. 2dB, the isolation is better than 20dB, the return loss is better than 20dB and two way unbalance is less than 依0. 5dB from 90 to 100GHz.