The invention discloses a ultrahigh-strength and low-inverse segregation CuNiSn elastic copper alloy. The ultrahigh-strength and low-inverse segregation CuNiSn elastic copper alloy comprises the following components (in percentage by mass): 14.5-22.0% of Ni, 4.5-8.5% of Sn, 0.3-0.6% of Mn, 0.05-0.2% of Mg, 0.1-0.15% of Ce, 0.01-0.10% of B, 0.01-0.1% of Sr, 0.01-0.1% of V, and the balance of Cu andinevitable impurities. The ultrahigh-strength and low-inverse segregation CuNiSn elastic copper alloy is reasonable in component, high in alloying degree, simple in production process, convenient tooperate and low in production cost. The prepared alloy has such characteristics as ultrahigh strength and high stress relaxation resistance; compared with a reported CuNiSn elastic copper alloy, an ingot prepared by a casting method can prominently reduce inverse segregation of Sn, the component controllability is high, the uniform annealing time is prominently shortened, and the energy is saved;and meanwhile, compared with beryllium bronze, the alloy has such advantages as high strength, excellent electric conductivity, high stress relaxation resistance and no poison element (such as beryllium). The ultrahigh-strength and low-inverse segregation CuNiSn elastic copper alloy is particularly suitable for high-performance electric conduction elastic devices in the spaceflight, aviation and microelectronics industries.