Abstract: Through the multiple frequency amplification, THz multiplier chain can obtain high stability, low phase noise terahertz signal from the low frequency microwave signal. In order to improve the power of the V-band frequency source, 4-way multiplier power combining was proposed. Combining analysis of electromagnetic field theory and three-dimen-sional electromagnetic simulation software HFSS and ADS, the design performance and efficiency of the source were analyzed. The experimental results show that output power is above 20dBm in range of 66 ~ 75GHz, the maximum power is 24dBm, and the synthetic efficiency is above 85%.