The invention relates to a multi-unmanned aerial vehicle detection task allocation and trajectory planning joint-optimization method and device. According to the method, the types of current execution tasks, the weather conditions during task execution, the information of areas to be detected and information of fixed-wing unmanned aerial vehicles are obtained firstly according to the situation that the fixed-wing unmanned aerial vehicles execute operation tasks in multiple areas to be detected, and then the optimum solution making preset models obtain maximum total benefits based on the preset models and algorithms according to the information and is regarded as a task allocation and trajectory planning result of the current operation. By adopting the method, tasks and trajectory plans of the unmanned aerial vehicles in the current operation can be automatically obtained according to the preset models and the algorithms so that the unmanned aerial vehicles can automatically execute the operation tasks according to the tasks and trajectory plans, the maximum total benefits can be also obtained while the situation that the unmanned aerial vehicles are not collaborative mutually is avoided, and accordingly the operation efficiency can be effectively improved.