Owing to the complex structure of Karst cave and the particularity of the environment,3D laser scanning technology has advantages of high precision, high efficiency and high density in data acquisition compared with traditional manual mapping technology. Although by 3D laser scanning we could quickly obtain the holistic 3D point cloud data of Karst cave, we could not meet the requirements for scanning some stone carvings and sculptures in the cave limited by the precision of laser point cloud. In view of this, we combined 3D laser scanning with image-based modeling technology to achieve complementary advantages. First of all we introduced the advantages and characteristics of the two technologies, and then researched the method of fusion and reconstruction of 3D model of karst cave from its work principle and data processing procedure. Finally, we evaluated the joint’s deviation of model fusion. Practice demonstrates that the fusion of 3D laser scanning and image-based modeling is feasible in Karst cave modeling and measurement as it could build up a realistic 3D cavern model with maximum efficiency and satisfactory accuracy.