A large amount of hydrogen would be generated because of zirconium-water reaction during serious accidents in nuclear power plant (NPP). Hydrogen could be combusted or explode under certain conditions, resulting in damage of the containment integrity and releasing radioactive substances into surrounding environment. Therefore, hydrogen elimination inside the NPP containment is an important subject. According to the requirements of NNSA (National Nuclear Security Administration), enough passive hydrogen recombiners (PHR) had been installed in unit 3&4 of Qinshan phase II NPP to prevent the hydrogen explosion in a serious accident. Additionally, new PHRs for unit 1&2 were also added. This article introduces the practical experience for the PHR modification, the comparisons between unit 1&2 and unit 3&4.