Based on the mathematical model and computational edge detection theory of Canny,an optimal operator for edge detection in computed tomography image processing was proposed in order to resolve the accuracy and efficiency problem in blade edge detection from computed tomography images.The quantitative analysis and simulation of standard images verify that,the performance of the optimal operator is better than the conventional operators in the signal-to-noise ratio(SNR),location and multi-response.The performance of the optimal operator is also verified by the practical computed tomography images.It is found that the edges of blade detected by the optimal operator are smoother,the noise points and false edges are less.