The crystalline silicon/amorphous silicon heterojunction (HJT) solar cells have attracted much attention due to their advantages of high open-circuit voltage, high conversion efficiency and low temperature coefficient. As the emitters of cell, boron-doped p-type amorphous silicon (p-a-Si∶H) thin films play an important role in achieving high conversion efficiency. By changing the boron doping concentration, the electrical properties of the p-layer can be adjusted, and therefore the conversion efficiencies of solar cells are directly affected. In this article, plasma enhanced chemical vapor deposition (PECVD) device was used to deposite amorphous silicon thin films applied in the crystalline silicon/amorphous silicon HJT solar cells. By changing the doping concentration of B2H6, p-a-Si∶H layer in the cells was optimized. As a result, the relative efficiency of HJT cell was improved by 0.75%. Further, gradient doped double-layer emitter structure was adopted. An improvement of 400 μs and 3 mV could be achieved for the minority carrier lifetime (@Δn=5×1015 cm-3) and implied Voc (@1-Sun) respectively. Eventually benefiting from an obvious boost in FF and Voc, the efficiency of the solar cells was increased by 2.03% relatively and an optimized p-type emitter process was therefore established.