The invention provides an eccentric ball valve. The eccentric ball valve comprises a valve body, a valve cover, a valve ball and a valve seat; the valve body is provided with a middle cavity and a first fluid channel communicating with the middle cavity; the valve cover is detachably connected with the valve body and is provided with a second fluid channel; after the valve cover and the valve bodyare connected, the second fluid channel communicates with the middle cavity; the valve ball is rotationally installed inside the middle cavity through an operation mechanism and is provided with a valve ball sealing face; the valve seat is installed on the valve cover and is provided with a valve seat sealing face capable of extruding the valve ball sealing face to seal the second fluid channel;and the valve seat is installed on the valve cover through an adjustable installing structure in a manner of being capable of finely moving, under driving of the operation mechanism, the valve ball rotates to enable the valve ball sealing face and the valve seat sealing face to be in extrusion contact gradually, the valve seat can finely move, and even-pressure sealing can be achieved between thevalve ball sealing face and the valve seat sealing face. By means of the eccentric ball valve, continuous abrasion of the valve ball and the valve seat can be avoided, and the good sealing performanceis achieved.