Abstract: A novel adaptive integral method (AIM) combined with the Maehly approximation technique is proposed to analyze the radar cross section (RCS) of targets in spatial domains. Compared with the conventional method, the Gauss interpolation operator is utilized to calculate the projection coefficients in the improved algorithm which makes computer programming easy to implement. According to the Maehly approximation theory, the RCS of targets at any angle within the given spatial range can be acquired fast. Numerical results show that the presented method reduces the storage requirement and the solution time without accuracy loss.