Abstract: 3D geological modeling can realize the intuitive and complete expression of the spatial relationship among geological bodies, therefore it is an effective way to achieve the scientific management and sharing of geological information. At the same time, a well-established 3D model supports slices in any direction, which can predict the shape of unknown areas and infer structural history. This paper constructed a 3D crustal structure model of the Longmenshan fault zone by collating existing 2D geophysical data, and analyzed the model with the measured Bouguer gravity anomaly data. The result show that the overall gravity field of the formation model is basically consistent with the measured Bouguer gravity anomalies, which preliminary proves the correctness of the model. The local gravity field shows that the sedimentary layer contributes less to the change of the overall gravity field with the scale of the model. The middle and upper crust develops uplifts and depressions to different degree, which coincides with the existence of low-velocity anomalies revealed by previous researches. The gravity anomaly gradient zone regular monotonously rises from northwest to southeast, which is consistent with the trend from previous inversion results, thus basically proving the reliability of the model. Furthermore, we do model inversion under the constraint of gravity data, and the model was modified.