Barrier height Φ and ideal factor n are important parameters for forward transport of merged PIN/Schottky (MPS) diodes, and softness factor is one of the indication of MPS reverse recovery. The structure simulation of 6H-SiC based MPS diode is carried out to verify the existence of double barrier and study the effect of temperature on the forward and reverse characteristics. Results show that in forward bias voltage, the barrier height 1 decreases and the barrier height 2 increases with increasing temperature, while both n1 and n2 decrease with increasing temperature. Because there are multiple composite transport mechanisms in the barrier region 1, and thermionic emission transport is the main transport mechanism in the barrier region 2. Under reverse bias voltage, the reverse recovery peak voltage and peak current increase with increasing temperature, but the softness factor gradually approaches 1.