The reinforced concrete U-shaped composite beam which is composed of precast U-shaped beam, precast slabs and cast-in-place (CIP) concrete, is investigated in this paper. The performance of the reinforced concrete U-shaped composite beam and the cast-in-place concrete control specimen subjected to positive moment was evaluated in terms of failure pattern, flexural strength of normal section, ductility and slips based on the monotonic static loading tests. The results showed that both specimens behaved in ductile manner. The flexural strength of reinforced concrete U-shaped composite beam was about 11% lower than that of the control specimen. The displacement ductility and curvature ductility of the precast specimen were about 33% and 18% lower than those of corresponding control specimen, respectively. The slip between precast beam and precast slab and the slip between precast slab and CIP concrete were less than 0.16mm and 0.17mm, respectively. The results in this paper are useful to expand the application of reinforced concrete U-shaped composite beam in the field of civil engineering.