In this paper, an E-plane stepped-impedance transformer and Y-junction bifurcation are used to form a waveguide power divider with ceramic substrate loaded with thin film resistors. This structure is realized high isolation in V-band by inserting a ceramic substrate at the H-plane center of the Y-junction waveguide bifurcation, both sides of which loaded with thin film resistors. The waveguide power divider was fabricated with aluminium-50% silicon, and has characteristics of light weight, lower coefficient of thermal expansion, good thermal conductivity, and its properties are more compatible with those of ceramic substrate. The principle and design procedure are described in detail. A V-band E-plane waveguide power divider is designed, fabricated, and measured. The measured results show that insertion loss is less than 0.4dB in the frequency range of 50∼60GHz, with typical isolation levels of 25dB between the two output ports and amplitude imbalance less than 0.19dB, phase imbalance less than 1.4°. The measured and simulated results show good amplitude, phase, and isolation characteristics validating the proposed power divider.