A 150 GHz high output power frequency doubler is designed and realized based on six anodes in anti-series GaAs planar Schottky varactors. The doubler is utilized by balanced construction. Co-simulation of 3-D electromagnetic simulator with nonlinear harmonic balance tool is utilized to improve the precision of simulation. According to the design results, the 150 GHz high output power frequency doubler is fabricated and tested. The measured efficiency is above 7% in 146 GHz-158 GHz. The peak efficiency is 12% at 154 GHz, and the output power is 71 mW.