The general expressions of the ground resolution and the telescope focal length for an imaging spectrometer were deduced to investigate the increase of energy integral time with motion compensation.The ground resolution is inverse proportion to the pointing angle for the imaging spectrometer with the motion compensation.It will decrease when the pointing angle increases,and vice versa.By giving a pixel size of 20 μm for a detector,an orbit altitude of 600 km and a beam deflexion angle low than 30° for the imaging spectrometer, the effective focal length of the telescope was calculated(400,470 or 435 mm),and the relation curves between the relative ratios of ground resolution and the beam deflexions were presented.On the situation of certain integral time, the expression of anti-scanning angular velocity of the pointing mirror was deduced.The result indicates that the anti-scanning angular velocity of the pointing mirror is the functions of the velocity of secondary planet,orbit altitude,the beam deflexion angle ahead of schedule on gazing an object,aviation time and the radius of the earth.The integral time will increase by N times when anti-scanning angular velocity of the pointing mirror is changed.