The development status of optical reconnaissance mission payload technology of large UAVs at home and abroad is introduced.To meet the requirements of ground resolution capability performance index for various types of optical reconnaissance mission payload of large UAVs,an equivalent ground resolution performance index conversion method is proposed.The design idea and layout method of ground resolution test targets are defined,and the intuitive and objective evaluation methods of ground resolution are given,so as to realize the quantitative testing and evaluation of ground resolution capability of large UAVs.The engineering flight test shows that the evaluation method is reasonable,scientific and accurate,and can be used to verify the ground resolution performance index of various types of optical reconnaissance mission payload of large UAVs.