Abstract: The effect of post-deposition hydrogen plasma treatment（HPT）to the intrinsic hydrogenated amorphous silicon（a-Si:H（i））passivation layer on the performance of the silicon heterojunction（SHJ）solar cell with high efficiency（＞23%）was investigated. It was found that HPT with an appropriate time could improve the passivation effect slightly and thus increase the solar cell efficiency.However,HPT with an over-long time obviously made the passivation effect deteriorate and the effective minority carrier lifetime（τeff）decrease. The analysis demonstrated that with the increase of HPT time,more and more hydrogen atoms entered the a-Si:H（i）layer,resulting in the SiH2amount increase in the layer. The microstructure factor（ R）of the layer increased and the layer quality became poor. The results indicated that the HPT process should be controlled carefully when the original solar cell efficiency was high since the solar cell performance improvement from HPT was limited in such a case.