Abstract: The physical simulation experiment of true triaxial hydraulic fracturing serves as a crucial method to investigate the fracture propagation behavior in tight reservoirs during hydraulic fracturing. However, current methods for characterizing fractures in laboratory experiments face challenges such as coarse particle size, practice difficulties, and unclear characterization of fracture morphology. Based on the fracture point cloud data obtained through laser scanning, a three-dimensional fracture reconstruction method based on the radial basis function–partition of unity method (RBF-PUM) was proposed, which achieved the hole fixing and high-precision reconstruction of the fracture point cloud. The geometric characteristics of fractures were quantitatively characterized by two indicators: fracture area and fracture roughness. Through a case study of the tight conglomerate reservoir of Baikouquan Formation of Mahu in Xinjiang, the fracture propagation law under the conditions of different gravel particle sizes and arrangements, horizontal stress difference, cluster spacing, and pump rate was analyzed. The results indicate that the average reconstruction error of the RBF-PUM method is only 0.56 mm, enabling precise restoration of complex fracture morphologies. The increase in gravel particle size and random arrangement can enhance the area and roughness of the fracture surface. Under low stress difference conditions, the fractures are more likely to communicate with the weakly cemented surfaces, forming complex non-planar fractures. Variable pump rate fracturing can balance the complexity and expansion scale of fractures, while reducing the cluster spacing will intensify the interference between fractures. The research results show that the RBF-PUM method has high reconstruction accuracy and can quickly and intuitively quantify and characterize the morphology of hydraulic fractures in tight reservoirs. It provides a new digital method for analyzing the fracture propagation laws and evaluating the fracturing effect after hydraulic fracturing experiments.