The invention provides a test device which simulates a
satellite in-
orbit state and separates two independent
stars A and B through unlocking and separating devices on the ground and a detecting method. According to the scheme, a simulated star A is suspended by a structure mainly, and is unloaded gravitationally so as to simulate a test environment during separation of the star A and the star B;an unlocking bolt is unlocked by
gas separation equipment, and the simulated star A acquires an upward thrust through a separating spring; by a
pulley block and a balance weight mode, the gravity of the simulated star A is balanced; and by T-Prob of a
laser tracker, position postures (x, y, z, alpha, beta, gamma) of the simulated star A in a whole upward movement process are acquired in real time.The test principle is simple, and the test device is easy to operate; an in-
orbit state can be simulated, and gravitational balanced unloading to a
spacecraft is realized effectively; a separation
route is not lower than 80 mm; a balance force in the
route is stable, and deviation is not greater than 0.1%; and a separation
route is finished, the gradient of a
system is smaller than 1 degree, andthe stability of the
system is good.