UAVs (Unmanned Aerial Vehicles) have the characteristics of low cost, no risk to human life, easy and simple operation, flexibility and reliability, which have been developed rapidly, exhibiting great potential in civil and military fields. Similar to other social systems, the task allocation of UAVs is the key technology of swarm UAVs applications, i.e., to preset and manage the tasks based on the UAVs amount and task load, which can be used to determine the application effectiveness of UAVs. This paper investigates the typical UAVs task allocation models and solution methods, analyzes the development trend & difficulties, which is of great significance on the development of the swarm UAVs task planning technologies.