Abstract: The traditional vane plumbs with the inside surface of a baffle, but the new-style vane designed in this paper inclines toward the inside surface of a baffle. The reflective light from the incident parasitic light and part of the stray light is blocked in the interbedded space of the new-style vanes and inside surface of baffle to be attenuated, and most of the residual light is retro-transmitted to the optic system, so just tiny stray light is able to arrive at the detector. The inclining angle of the new-style vane must keep the distribution that is bigger than which is the included angle of the incident stray light with the baffle. Only by the distribution can the inclining stray light be avoided to arrive at the optic system directly. Taking the Cassegrain space camera as an example, two types of vanes were set up respectively within external baffles of the two cameras, and then the modeling and simulation for the two structures were performed by the aid of Tracepro software. The results show that the space camera with the new vane is 4 grades higher than that with the traditional vane.