Abstract: Based on the EM field full-wave analysis method, an E-plane waveguide power divider on Y-structure in V band has been proposed. By employing multi-section stepped-impedance waveguide transformer, a wider bandwidth has been achieved. A resistive septum loaded ceramic substrate is inserted into the central H-plane of the waveguide divider to realize high isolation. The waveguide power divider is made by aluminium-50% silicon, and has characteristics of light weight, low thermal expansion coefficient, good heat conductivity, and matched well with ceramic substrate. The test results show that insertion loss is better than 0. 4 dB in the frequency range of 50~60 GHz, with typical isolation levels of 25 dB between the two output ports,amplitude imbalance less than 0. 19 dB, phase imbalance less than 1. 4°. The designed power capability of the power divider is as high as 33kW. Finally, the power dividers are validated by the reliability experiment, and the results indicate that the power divider has good reliability and is potential for engineering applications.