Lost circulation is a phenomenon in which a large amount of drilling fluid is lost into the formation during the drilling process, and the morphology and multi-scale characteristics of the formation fractures are essential factors affecting the degree of drilling fluid lost and the efficiency of fracture plugging. Most of the research on fracture plugging is aimed at single-width fractures, and the fracture morphology is usually simplified. In this paper, the 3D scanning, 3D reconstruction and 3D printing technologies were used to observe the plugging performance of lost circulation materials (LCMs) in complex fracture formations. The Joint Roughness Coefficient (JRC) and fractal dimension were calculated based on the fracture surface point cloud data obtained by 3D laser scanning technology, which can realize the quantitative characterization of fracture surface morphology characteristics. The fracture plugging evaluation method was established by combining 3D reconstruction and 3D printing technologies, which can simulate the actual fracture morphology characteristics and the coexistence conditions of various fracture widths. The multi-scale fracture simulation samples with various widths and actual morphology characteristics were prepared. Based on the prepared multi-scale fracture simulation samples, complex fracture plugging simulation experiments were carried out to clarify the plugging behavior of LCMs on multi-scale fractures. The experimental results show that the effective retention of LCMs and the high pressure-bearing capacity of the plugging zone are essential to successful plugging. The retention capacity of LCMs in fractures can be improved by appropriately reducing the particle size of rigid LCMs. On this basis, further compounding elastic particles and fiber materials insert improves the pressure-bearing capacity of the plugging zone.