Abstract: Aiming at the optimization of sea sand particle grading, four kinds of sea sand, A, B, C and D with different particle sizes, were used as four variables. The fluidity model, compressive strength model and flexural strength model with statistical significance were established.The response surface methodology was used to analyze the effects of sea sand on the fluidity, compressive strength and flexural strength of ultra-high performance concrete (UHPC) . Through the multi-objective optimization of the models, the optimization plan for the amount of sea sand of each particle size segment was obtained.The UHPC with good fluidity, 28 d compressive strength over 130 MPa and flexural strength exceeding 29 MPa was prepared.