This paper presents a 26GHz power amplifier for high band 5G application in 65nm CMOS technology. By using three stage differential common source topology plus final four-way power combiner, 24dB gain of PA is achieved at millimeter wave frequency. Capacitors, Complicated inductors and transformers scheme provide good matching for input, inter-stage and output at 26GHz band. Simulation results demonstrate the PA with of 15.6 dBm, of 13.3 dBm, and peak PAE of 24.44%. Its -3dB bandwidth covers 4GHz, with better than 10dB input/output return loss across band. It consumes 74mA from a 1.5V supply.