The emission layer of β-FeSi2(n)/c-Si(p) solar cell was simulated by AFORS-HET software in gradient-doping and the influence of gradient doping and uniform doping on the conversion efficiency of cells for the same total amount of doping in emission areas was studied. For gradient doping, the influences of emission energy band, emission concentration difference and layer number in emission areas on the conversion efficiency of cells were discussed respectively. The experimental results showed that the use of gradient doping in emission areas could significantly improve the conversion efficiency of cells. With the increase of concentration ratio of each layer in emission areas, the conversion efficiency of cells increased first and then remained unchanged; with the increase of layer number in emission areas, the conversion efficiency increased first and then remained unchanged too; and with the increase of thickness of emission areas, the conversion efficiency decreased gradually. The total increase amount of conversion efficiency of gradient-doped cells was far greater than the total decrease amount of conversion efficiency caused by over thick emission areas.