Abstract: Under the approach of numeral simulation, this paper firstly aims to carry out the simulating calculation work of value under different operating conditions and value lift, and then analyzes the erosion damage of the internal components of the value, which include value core, cage and seat. From this research, we can find that the extent and the location of the erosion are directly affected by the opening degree of the value. When the distance between the value core and seat is deliberately 20 mm, the upstream face of the value core erodes most seriously. When opening degree is small（2-20）, the side face and conical surface are scoured the most, and the erosion degree is inversely proportional to its opening degree. When the opening degree is larger（40mm）, the cage orifice is eroded the most. Under the same flowing condition, the opening degree of the value is inversely proportional to the degree of erosion, and the conical surface of the value core and the cage outlet is vulnerable to erosion.