The performance of β-FeSi2(n)/a-Si(i)/c-Si(p)/μc-Si(p ) HIT heterojunction solar cell is simulated and the parameters of each layer of the solar cell are optimized. The simulation results show that the performance of the solar cell can be improved remarkably by adding an intrinsic thin-layer and BSF to the FeSi2(n) /c-Si(p) solar cell structure. When defects are introduced and the parameters are optimized, the ultimate parameters of the solar cell are: VOC=647.7 mV, JSC=42.29 mA·cm-2, FF=75.32%, EFF=20.63%. The efficiency of the FeSi2(n)/c-Si(p) solar cell is improved by 2.3%.