This paper investigates SiC power semiconductor devices in a three-phase active front-end Boost PWM rectifier for power conversion efficiency improvement. Different from Si IGBT based Boost PFC rectifier, the SiC MOSFET based Boost PFC rectifier can achieve the synchronous rectification by MOSFET channel reverse conduction for efficiency improvement. The operation principle difference of three-phase active frontend Boost PWM rectifier with SiC MOSFET and Si IGBT is introduced. The switching characterizations of 1.2kV SiC MOSFET are provided. 5kW 380VAC input, 800VDC output three-phase active front-end Boost PWM rectifier prototype is built in lab to evaluate the efficiency advantage with SiC device. All SiC power semiconductor devices based circuit achieves about 1.2% more efficient compared with all Si devices, and around 0.5% more efficient than Si IGBT & SiC diode hybrid device pair for the three-phase Boost PWM rectifier due to low switching loss of 1.2kV SiC MOSFET and reduced conduction loss from the synchronous rectification operation for 1.2kV SiC MOSFET.@en