In order to rapidly expand the study of superconducting circuits in general circuit simulation software, according to the experiment data of MgB2/B/MgB2 Josephson junction prepared in our laboratory, a circuit model is established in Multisim, the simulation results comply with the measured property of the junctions. Based on the theoretical analysis, transient simulation for two different functions rapid single flux quantum (RSFQ) splitters is conducted. The simulation proves the simple and intuitive working process of the circuit, and verifies the theoretical analysis well. The results indicate that the simulator is a useful tool both in feasibility and efficiency for superconducting RSFQ circuits.