In a Loss-of-Coolant Accident (LOCA), the ballooning and deformation of zircaloy cladding can reduce the coolant flow area, which in turn impacts the heat transfer capability of the reactor core. Fuel performance codes, which primarily focus on anisotropic creep deformation during ballooning, may underestimate the extent of cladding ballooning, leading to an overestimation of the core's heat transfer capability, making the results less conservative. To improve the accuracy of cladding burst strain prediction in LOCA analysis, a thermal–mechanical coupling modeling method was developed based on the finite element framework. The present work incorporated anisotropic plasticity, high-temperature anisotropic creep, and high-temperature phase transformation. The proposed method was validated against uniaxial tensile mechanical tests conducted by the Pacific Northwest National Laboratory (PNNL) and cladding burst tests conducted by the Oak Ridge National Laboratory (ORNL). The results showed that anisotropic plastic deformation played a significant role in cladding ballooning. The present methodology with anisotropic plasticity could provide better predictions of cladding burst strain in the medium to high pressure range near a LOCA accident, which could help to better understand the cladding ballooning behavior during LOCA.