In order to investigate the bending performance of UHPC prefabrication and assembly beams,8 beams were designed and the static load experiments carried out , including 6 UHPC prefabrication -assembly beams which had different lapped lengths, an ordinary concrete prefabrication assembly beam and a cast-in-situ concrete beam to analyze the impact of different lapped lengths to the UHPC prefabrication -assembly beams. The results showed that the failure mode of the prefabrication- assembly beam were similar to the contrast beam，the cracks were distributed evenly over ordinary concrete precast segments. With the increase of lapped length, fracture spacing decreased; the ratio of the measured and calculated values of the bearing capacity of UHPC prefabrication- assembly beam were greater than 1.36, far more than that of ordinary prefabrication- assembly beam ;increasing the lapped lengths of steel had little influence to improve the cracking load of UHPC assembly beams, when the lapped length for 10d, the bending performance of UHPC prefabrication - assembly beams were basic similar to the cast-in-situ concrete beam.