The invention discloses composite concrete for construction of an ultra-long pool. The composite concrete comprises the following raw materials by mass: 180-260 parts of Portland cement PO42.5, 70 to80 parts of slag S95, 70 to 80 parts of II-grade coal ash, 680 to 750 parts of yellow sand, 1000 to 1100 parts of broken stone, 4.5 to 6.0 parts of an additive, 170 to 190 parts of tap water and a certain amount of anti-cracking fibers. According to the composite concrete R7 for construction of the ultra-long pool, standard curing strength is 21.8-28.6 MPa, 28-d compressive strength is 33.1-43.4 MPa, a slump retention value is 145-150 mm, an impermeability grade reaches the P8 grade, and apparent density is 2320-2340 Kg/m<3>. Since the concrete has high compression resistance, impermeability and crack resistance and good fluidity, the requirements of ultra-long pool construction for concrete slump, impermeability, crack resistance and the like are met.