A detection method for space-based targets was brought forward.By forecasting the motion track using a land-based radar,the space-based detector could operate in a high reliability and could obtain a better probability for target acquisition with joint detection by infrared pointing,active laser and visible detection.At the conditions of effective aperture of 0.5 m and the limiting effetive load,the conclusions are as follows:when the normal sunlight,visible detection of CCD has obvious advantage in detecting distance,the fusion result is mainly decided to visible detection.At the cases of irradiation angle ≥90° or without sunlight,the joint detect ability is concerned with laser beam divergence angle.When beam divergence angle ≤0.5 mrad,active laser is better than infrared detection.It means that this paper provides a reliable solution for space-based detecting and pointing.