We present a set of vulnerability assessment methods of physical protection system (PPS) of nuclear power plants after investigating and collecting the experience of assessment in China. The methods have important significance to strengthen and upgrade the security of the nuclear power plants, and also to We present a set of vulnerability assessment methods of physical protection system (PPS) of nuclear power plants after investigating and collecting the experience of assessment in China. The methods have important significance to strengthen and upgrade the security of the nuclear power plants, and also to