Abstract: The shrinkage cracks of the Ultra-High Performance Concrete (UHPC) in the early stage due to its low water-binder ratio and high content of cement materials. In order to address this issue, this paper investigated the effects of two admixtures (shrinkage reducer and expansion agent) on the properties of UHPC. The research results showed that both the shrinkage reducer and the expansion agent inhibited the early self-shrinkage of UHPC. The shrinkage effect of the shrinkage reducer was greater than that of the expansion agent. The shrinkage reducer could improve the fluidity of UHPC, and had a relatively small impact on the mechanical properties of UHPC. At a 1.5% dosage of the shrinkage reducer, the 72 h shrinkage rate of UHPC was 686 με, the fluidity was 215 mm, the 28 d compressive strength was 165.2 MPa, and the 28d flexural strength was 33.4 MPa. The research results have certain reference and application value for improving the toughness enhancement performance of UHPC.