Abstract: In order to obtain the design parameters required during the antenna capturing process in the satellite pointing control of the relay satellite,the movement relation between relay satellite and user satellite was analyzed.The result proves that the time to capture of antenna is a function of the velocity of the user satellite relatively to the relay satellite.The relation curves and formulas between the antenna capture time,the capture rate and the velocity of user satellite were deduced after analyzing and calculating the velocity of the user satellite relatively to the relay satellite.