Ultra-high performance concrete (UHPC) was prepared by ultrafine and highly active mineral admixtures (ultrafine admixtures) and silica fume in single or compound admixture. The effects of ultrafine admixtures with different dosage on the workability, mechanical properties, hydration heat and shrinkage properties of UHPC were analyzed. The results show that the fluidity of UHPC increases with the increase of the ultrafine admixtures, and the highest fluidity of jumping table is 275 mm. When UHPC is prepared by mixing the ultrafine admixtures with 10% (mass fraction) silica fume, the flexural strength increases first and then decreases with the increase of ultrafine admixture, while the compressive strength increases first and then keeps steady. The maximum flexural strength and compressive strength are 25.9 MPa and 150.0 MPa, repectively. The hydration heat of UHPC cementitious material prepared by compounding ultrafine admixture and 10% (mass fraction) silica fume increases at first and then decreases with the increase of ultrafine admixture. The early shrinkage of UHPC prepared by compounding the ultrafine admixture and silica fume with a mass fraction of 10%, is the smallest, which is 50.92% lower than that of UHPC prepared by silica fume with a mass fraction of 20% alone.