In this paper, we analyze photometry of V504 Cyg semi-detached binary system. For this purpose, after taking the photometric data, primary and secondary minimum and new epoch were calculated. The pe- riod of system is found to be 0.3516916 day. Analysis of light curve was performed by PHOEBE software which uses last version of Wilson–Devinney code. 3D model of the system is worked out using Binary Maker software. The O’Connell effect in the light curve is observed and an accurate model of this system is presented by introducing four spots on the components.
