To study the lap splice length of U-shaped rebar loop in precast concrete structure, three fabricated specimens with different lap splice length and one cast-in-place beam-column joint comparison specimen were carried out for low-cycle repeated quasi-static tests. By observing the failure modes of each specimen, the corresponding hysteretic behavior, bearing capacity, deformation capacity, and the stress development process of reinforcement were studied, and then the reasonable lap splice length of U-shaped rebar loop in precast concrete structure was analyzed. The results show, (1) the bearing capacity of fabricated joints is higher than that of cast-in-place joints; (2) the ductility and energy dissipation capacity of specimens with different lap splice length are different; (3) the increase of lap splice length is conducive to the improvement of the bearing capacity, ductility, and energy dissipation capacity of specimens. Finally, based on the test results, the reasonable lap splice length of U-shaped rebar loop is fitted and regressed, and then the suggestions for the optimal design of the joint of the lap splice length of U-shaped rebar loop in precast concrete structure are putting forward.