The meso-mechanism of crack propagation in jointed loess was investigated using the particle flow code PFC2D, which simulated uniaxial compression tests on nonpersistent jointed loess. Numerical results showed good agreement with experimental data. On this basis, further analysis of crack evolution during different loading stages was conducted from the perspectives of stress fields, displacement fields, and energy perspectives. The results demonstrate that crack propagation progress can be divided into three phases: phases I and II dominated by wing cracks, and phase III characterized by halted wing crack growth and rapid secondary crack coalescence. Wing cracks extend vertically under tensile stress, whereas secondary cracks develop under combined tension-compression stress. Wing cracks represent tensile fractures driven by DF-II displacement fields, and secondary cracks form tension-shear fracture zones through multi-type displacement fields. Accelerated crack growth correlates with rapid elastic strain energy release and exponential growth in dissipated energy.