It is difficult for conventional single population-based evolutionary algorithms (conventionalevolutionary algorithms-CEAs) to solve epistatic interaction problems. Based on computational model ofcooperative coevolution inspired by the coevolutionary phenomena of natural species, a coevolutionary algorithm (CoEA) for solving NK-landscape. problem is proposed. Some problems related to the interactions among species and individual s fitness computation are discussed. Mathematical analysis shows that the exponential increase. index of CoEA is higher than that of CEA for a schema which fitness is higher than the average fitness of population.Simulation results verify the theoretical result,and show that the coevolutionary algorithm is more efficient and effective than CEA in solving epistatic interactions problems.