An osmotic pump controlled release tablet and the preparation method thereof are disclosed. The osmotic pump controlled release tablet is composed of tablet core, semipermeable membrane and optional film coating. The material of said semipermeable membrane is composed of ethyl cellulose and povidone in the ratio of 1:1~1:4 by weight. Said tablet core comprises drug containing layer and push layer. The osmotic pump controlled release tablet also characterizes in that (1) the angle θ1 formed by the outer curved surface of the drug containing layer and the lateral surface is 120°-180° and/or (2) the ratio of L1 to r is 0.27-1.0, wherein L1 is the vertical distance from the central vertex of the outer curved surface of the drug containing layer to the plane formed by the intersection line between the outer curved surface of the drug containing layer and the lateral surface, and r is the radius of the tablet core.
