In this paper, a method of calculating the creepage distance of insulators based on 3D reconstruction technique is proposed. First of all, the TSDF data within the threedimensional voxel grid are obtained by the framework of KinectFusion algorithm. Then the effective contour points representing the creepage distance are extracted in the twodimensional section obtained by symmetrical cutting. Then we traverse the effective contour points to calculate the creepage distance of insulators. The innovation lies in the construction of threedimensional model of the insulator, changing the shape of irregular objects into voxel to compute and process. The experiments show that the method is fast and accurate, and the average error remained at about 2.7%. Validated by experiments, our approach can bring the convenience to the measurement and production. In addition, the repeated measurements due to the inaccurate result are avoided.