Аннотация:From an analysis of optical light curves a low-mass X-ray binary system Cal 87, situated in a Large Magellanic Cloud, the parameters of this system are determined. The model was used that contains the optical K-star, filling its Roche, and geometrically thick accretion disk. The disk has a thickening in the area of collision with the flow of the substance which flows from the optical components. Using all available to the present time data received that the inclination of the orbit of the system is at 83-86 degrees, the ratio of the masses of the component for the mass of the optical star МV ~ 0.6-0.7 M(sun) q = 9-11, and the mass of the compact object MX = 5.2-7.7 M(sun).