In this paper, the coupled motion of optical communication terminal and the satellite platform and its impact on the error of coarse pointing are studied The influence of the coupled motion on the distribution of the beacon optical filed is also analyzed When the moment of inertia of satellite platform is less than 100 kg-m2, the coupled motion induced beacon pointing error will reduce the received optical power and system redundancy greatly. Compensation processing must be required in this condition. When the moment of inertia of satellite platform is between 100 kg·m2 and 1000 kg·m2, the coupled motion induced beacon pointing error becomes less. Compensation processing must be used when the pointing angle is bigger. When the moment of inertia of satellite platform is more than 10000 kg·m2, the pointing error could be neglected.