Experimental study on the flexural behavior of PC composite slabs with boundary restraints at room temperature and after fire was conducted. The temperature distribution of cross-section during heating and cooling, the deterioration rules of the ultimate load, and the initial flexural stiffness and ductility index of specimens were investigated. Test results show that the failure modes for control specimen and specimens loaded after fire were both flexural failure. The temperature field of cross section exhibits as layer distribution during heating, in which the external temperature is high and the internal temperature is low. However, the cross-section temperature field shows circle distribution during cooling, in which the external temperature was low and the internal temperature was high. The ultimate load and initial flexural stiffness of composite slabs with boundary restraints after fire decreased with a curve like parabola. The residual deflection of composite slabs with boundary restraints after fire increased obviously. Based on the theoretical analysis results, the classical plastic hinge line theory was also suitable to PC composite slabs with boundary restraints at room temperature and after fire. The simulation results of cross-section temperature distribution and ultimate load of specimens after different fire duration were in good agreement with the experimental results. The research results can provide reference for the fire design and post-fire evaluation for PC composite slabs.