The traditional terahertz detector can only obtain the amplitude of signal. An orthogonal heterodyne mixing structure is presented, which can obtain the amplitude, phase and polarization information at the same time, and effectively improves the sensitivity and information of the detector. Based on 40 nm Complementary Metal Oxide Semiconductor(CMOS) process, the detector connects the inductors in series between the switch stage and the transconductance stage of the traditional Gilbert double balanced mixer structure. The cascode IF(Intermediate Frequency) amplifiers are cascaded to further improve the response voltage of the detector. After simulation and optimization, the voltage responsivity of 1 GHz IF signal is 1 100 kV/W and the noise equivalent power is 26.8 fW/Hz1/2 under the condition of -50 dBm RF(Radio Frequency) power and 0 dBm LO(Local Oscillation) power. The output waveform shows good orthogonality. Meanwhile, a 1: 8 power divider is designed to distribute the LO power. The insertion loss of the power divider is about 5 dB at 150 GHz. The amplitude difference of four-differential-output is 0.8~1.2 dB, and the phase difference is 0.4°~1.7°.