The invention discloses a puncture path planning method in CT guided liver tumor radiofrequency ablation. The method comprises the steps that three-dimensional structures of the liver tumor, the liverand key anatomical structures (large vessels, the lung, the heart, the stomach, the kidney, the gallbladder, skin and bones) are rapidly and automatically extracted from a CT sequence scanning imagein the liver tumor radiofrequency ablation, the end point of a puncture path is worked out, N points on the skin serve as potential starting points of the puncture path, N potential puncture paths areformed by the potential starting points of the puncture path and the end point of the puncture path, M potential puncture paths meeting the unreasonable potential puncture path conditions are removed, K alternative potential puncture paths (K=N-M) are left, scores under all score criteria are calculated for the K alternative potential puncture paths separately, comprehensive scores of all the alternative potential puncture paths are calculated finally, and the alternative potential puncture path with the highest comprehensive score serves as the output result of the puncture path planning method in the CT guided liver tumor radiofrequency ablation.