Fully-lined ball valve use a ball with a through hole as the opening and closing parts. The ball rotates with the stem around the central line of the body to realize the opening and closing. Special compression molding technology is adopted to make the sealing surface dense and good, and the combination of V-PTFE packing makes the valve zero leakage; the ball and the stem are cast as one, eliminating the possibility of the stem rushing out of the pressure parts due to pressure changes, and ensuring the safety in use; the use of fully-lined technology, make the valve strong corrosion resistance of the medium.