When concrete subjected to triaxial compression state while exposed to fire, a strain component different from the thermal strain is measured. This strain component is depended on the temperature and stress and commonly referred as Load Induced Thermal Strain (LITS). Accurately understanding and modeling LITS phenomenon is critical for a reliable evaluation of the thermo-mechanical coupling effects on concrete. In the current study, a multiaxial LITS model of concrete was innovatively developed. This model can predict the behavior of concrete subjected to wide applied load level ranging from 20% to 80% and temperatures up to 800 °C. A 3D LITS model was developed through a triaxial compression stress confinement implementation and Poisson’s ratio. Considering the water evaporation of concrete under high temperature, a third order polynomial LITS derivative function and an exponential derivative function were proposed to characterize the effects of the stress confinement and thermal effect. A comparison study was conducted between the numerical results of the proposed model with tests data in literatures, which indicated the reliability and accuracy of the proposed model. The sensitivity study of model parameters was conducted to analyze the impact of parameters on the development evolution of LITS under different load levels.