Abstract: The special fire furnace and experimental set-up were designed based on an one-span single storey composite steel frame. The deformation of 4 one-span single storey composite steel frames with different connections between the reinforced concrete and the steel beam in 2-type of fire conditions were studied. The temperature distributions along the composite beam sections, both in the columns and the reinforced concrete slabs, were measured. The displacements of the columns and the composite beams were recorded during experimental periods. It is found that the steel temperatures outside the concrete slab are almost equally, but the steel temperatures inside the concrete are different. The large difference exists between the steel temperature-time curves and the concrete temperature-time curves. The steel temperature rises and decreases more quickly than the concrete temperatures. There is a short plateau in the concrete temperature-time curves at about 100℃ because of the evaporation of water in the concrete. The deformations of the 4 frames and the deflections of the composite beams were studied particularly. At last, the engineering suggestion is given by comparing the fire-resistance behavior of the 4 composite steel frames.