In this paper, full-scale reinforced concrete slabs are analyzed under thermal-mechanical loads in fire conditions. The rectangular one-way slabs including a simply supported slab and a three-span continuous slab are concerned in the analysis. Finite element simulation is carried out by using the ABAQUS program to evaluate the non-uniform temperature distributions in thickness of the slabs and to analyze the deformation and stress redistribution of the slabs at elevated temperatures. Sequentially coupled thermal and structural analyses are performed to simulate the responses of the slabs in fire conditions. Deformation and strength of the slabs under thermal and mechanical loads are discussed. The numerical results are compared with the experimental ones and good agreements are observed. The analysis results show that the main reinforcement ratio has significant effects on the deformation and strength of the slabs at elevated temperatures and the three-span continuous slab has better performance of fire-resistance than the simply supported slab.