P-type hydrogenated microcrystalline silicon thin films have been prepared by radio-frequency plasma-enhanced chemical vapor deposition with B2H6 as a doping gas. The effects of substrate temperature and the doping ratio on the microstructure and dark conductivity of the p-type hydrogenated microcrystalline silicon films have been investigated. The results show that the films deposited at higher substrate temperature are amorphous even if the doping ratio is very low. The crystalline volume fraction of films monotonically decreases and the dark conductivity initially increases slowly and then decreases rapidly with substrate temperature increasing, which is very similar to the effects of the doping ratio. Finally the growth mechanism of p-type hydrogenated microcrystalline silicon thin films has been discussed in particular.