A new cooperative guidance law is proposed for target estimation of multiple unmamed aerial vehicles (UAVs) without involving numerical computational work. The guidance law derivation is based upon the Fisher Information Matrix (FIM) to quantify the amount of target information. For two UAVs, an analytical one-step determinant of FIM is introduced, which sufficiently reflects the trend of previous well-known optimal manoeuvers. Therefore, by considering only one-step information, as opposed to accumulated total information, a new feedback guidance law with intuitive physical analysis is induced and then its validity is verified by comparing it with the results of previous approaches. To apply the proposed idea to more multiple UAVs, a generalized formulation is derived as a weighted combination of each guidance law. Also, for more realistic application, the proposed guidance law is modified to deal with an avoidance problem of risk zone.