This article investigates a simplified model of tidal locking in celestial binary systems. The central body is assumed to consist of a solid spherical core and a uniform liquid outer layer, and the deformation of the central body under gravity is approximated as ellipsoidal. The precision of this approximation is also demonstrated. Finally, the article uses the “constant geometric lag model” to calculate the tidal torque relative to the centroid of the central body when the central body has a deviation angle of θ from its equilibrium position. The conclusion is that the tidal frictional torque between the two celestial bodies is proportional to the square of the revolving body^,s mass, the fifth power of the central body^,s average radius, and inversely proportional to the sixth power of the distance between the two bodies.