Gaussian smoothing filtering has a good performance in averaging the noise and preserving the edge.However，the large amount of calculation limits its application in real-time image processing system.Consequently，in view of the decomposability of the Gaussian smoothing mask，an optimized Gaussian smoothing filtering method which achieves successive convolution within single traversal is proposed in this paper.Firstly，reading 4×8 image area is as a basic operation unit to reduce data access.Secondly，lateral convolution is parallelly computed by using the inline function，to longitudinal convolution is calculated by recomposing and reusing lateral convolution results.Finally，the image with basic operation unit is traversed，smoothing filtering results are calculated.The experimental results show that the optimized code execution time is improved more than 35 times compared to the original C code when a 320×240×8bit image is smoothed based on TMS320C6455.The proposed method has great value in engineering application.