Based on conventional surface and upper-air observation data and ERA5 reanalysis data, a diagnostic analysis is conducted on two regional rainstorm events triggered by cold fronts in Guanzhong, Shaanxi, occurring from 15 to 16 July 2022 (“0715” event) and from 12 to 13 July 2023 (“0712” event). The results are shown as follows. (1) Both rainstorm events feature strong convective activities, accompanied by short-duration heavy precipitation. They occur in the area of high instability, characterized by high temperature and humidity on the periphery of subtropical high (SH), where the intrusion of cold fronts into eastern Guanzhong triggers convection. (2) There are differences between the two events. In the “0715” event, the South Asia high is stronger and the SH is positioned more northward, with stronger transfer of water vapor and weaker northerly wind in the middle-lower troposphere. The convection triggered by cold front is located further north, resulting in the rainstorm center being located on the edge of the Beishan Mountain. In the “0712” event, the SH is slightly shifted southward, with weaker transfer of water vapor and stronger northerly wind in the middle-lower troposphere. The cold front is blocked by the topographic barrier of the northern foot of the Qinling Mountains, resulting in the rainstorm. (3) The diagnosis of frontogenesis indicates that both events are accompanied by significant frontogenesis in the middle-lower troposphere. The secondary circulation triggered by frontogenesis promotes the development of low-level vertical motion and triggers convective instability energy. The heavy precipitation areas are mainly located near the ascending branch of the secondary circulation. (4) The frontogenetic structures differ between the two events. In the “0715” event, the intense frontogenetic zone extends to a higher height. The frontogenesis is mainly contributed by the horizontal divergence term and horizontal deformation term at 850 hPa, while the frontogenesis is mainly contributed by the diabatic heating term at 700 hPa. In the “0712” event, the intense frontogenetic zone is lower, and the low-level secondary circulation is stronger with its ascending branch shifted southward. The frontogenesis is mainly contributed by the horizontal divergence term, vertical motion tilt term and diabatic heating term.