In order to eliminate the deviation of the projection center of a spac e circle generated by perspective transformation,a novel method based on the principles of cross ratio and pole-polar relationship is proposed in this paper to locate the real projection center precisely using concentric circles.Firstly,the basic principles are introduced briefly,then the detailed procedures to locate centers are addressed,and lastly the accuracy of location and the impact factors of the acc ur acy are analyzed by experimental methods with simulated and real images.Experimental results indicate that the method can obt ain the real projection center of a space circle accurately and stably,and the positioning precision is always better than 0.2p ixel even under very harsh conditions,which has obvious advantages compared with the direct ellipse fitting method Besides,only simple linear computation is involved in our method,so it also has computational efficiency.Furthermore,the method can be employed wi th high generality due to any information about camera intrinsic or extrins ic parameters is not required and the physical models of the concentric circles are not necessary either.It concludes that our new method is valuable in theor y and practice for machine vision,visual measurement and some other fields.