A new isolator-high-speed mechanical rotating mirror isolator for high power laserfusion systems, is described in this paper. The isolator has a high isolating ratio and a low insert loss, and it can also acts as spatial filter and backward laser beam isolator. The problem of synchnization is investigated in detail. Our experiment shows that an isolator with a beam aperture of 40mm, and a rotative velocity of 6000rpm can achieve a timing accuracy of better than 0.3μs, and a restoring accuracy of better than 0.3 μs，and a restoring accuracy of better than 1". The factors affecting the accuracy are analyzed and methods of improvment are given.