Five-axis CNC machining tools can improve the efficiency and accuracy obviously in machining industries, but the machining errors and tool interference are likely to happen due to the complexity of tool motion. So the verification of the tool path is very important and necessary before machining the part. A new algorithm for 5-axis machining verification based on the stencil buffer has been presented in the paper. Based on the tool path and the cutter geometry, the cutter’s swept profile is determined. The swept envelope is subtracted from the sliced blank part model by using the stencil buffer. Considering the complexity of five-axis tool motions, examples are necessary to verify the reliability of the proposed algorithms. The experiment results indicate that the method is superior to the traditional methods on the processing time and the image quality. This proposed method can further be applied to machining error analysis, collisions interference.