Abstract: This paper analyzes the unmanned aerial vehicle(UAV) hierarchy and complex electromagnetic environment effects on UAV, and an efficiency evaluation index system of UAV in complex electromagnetic environment is established, the indexes are obtained using subjective weighting method and objective weighting method. Considering the fuzziness and uncertainty of UAV system indexes, the cloud model is used to get the combination between the qualitative and quantitative attributes of indexes, which effectively combines the fuzziness and uncertainty factors in the course of evaluation, and the total effectiveness of UAV in complex electromagnetic environment system is fitted using evaluation level cloud model. Finally, the method of effectiveness evaluation of UAV in complex electromagnetic environment is established based on cloud model, which provides a reference foundation for the quantitative efficiency evaluation of UAV in complex electromagnetic environment.