Abstract: Based on Fourier’s heat transfer theory, the modified function of moisture over the temperature regions of water evaporation was proposed to establish the improved model of temperature field. According to the nonlinear shell theory and thermal elastic-plastic constitutive model, the numerical model and existing calculation program were developed to trace the behavior of two-way reinforced concrete slab in fire. The reliabilities of the numerical model and program were validated by test results. Furthermore, the model was used to investigate the effect of fire scenario, restraint, aggregate type, slab thickness and concrete cover on the deflection and fire resistance of two-way reinforced concrete slabs. The results from the parametric studies indicate that the fire scenario, aggregate type, slab thickness and concrete cover have significant effects on the fire resistance of RC slab. The deflection and failure mode are very sensitive to the restraint of the slab, and the mechanical mechanism is very complex.