This paper addresses a cooperative jamming resource allocation problem in electronic warfare and presents a resource allocation model of cooperative jamming (CJRA). Besides the capabilities and number of available jamming resources, the model also takes many constrains into account. Then an improved immune genetic algorithm (IIGA) is presented to solve the problem. In order to prevent the algorithm from converging too slowly like traditional immune genetic algorithm, IIGA introduces the mechanisms of immunological memory and immunological metabolism which can restrain the individuals from degenerating in the process of evolution. In the end, the simulation indicates that the algorithm can resolve the problem of CJRA effectively and shorten the time of decision-making.