The three piece stainless steel ball valve comprises a valve body and a valve seat, and an O-ring connector is arranged between the valve body and the valve seat. The valve body and valve seat of the ball valve are connected by an O-ring connector for easy connection and good sealing. Three piece ball valve is a new type valve widely used in recent years. The working principle of the ball valve is to make the valve unblocked or blocked by rotating the valve. The ball valve is light to open and close, small in size, can be made into a large diameter, reliable in sealing, simple in structure, and convenient in maintenance. The sealing surface and spherical surface are often closed, and are not easy to be eroded by the medium. It is widely used in various industries.