Force behaviors of the loading platform of rotating stereo garages is analyzed, equations describing the load capacity and the deformation limit state are proposed for the key sections by applying the second-order moment into the reliability analysis of the main beam. Considering random parameters subject to normal distribution, a reliability model of the main beam of the loading platform is set up based on multiple failure modes and the reliability is analyzed and calculated by using second-order moment. Simulation results show that the reliability model is significant to guide designing on the reliability of rotating stereo garages and improves rotating stereo garages.