The invention provides an automatic flight route selecting method and device. The method comprises the steps that a preset flight route library and the real-time flight information of an airplane are acquired, wherein the flight route library comprises a number of preset flight routes; a flight route closest to the real-time flight information of the airplane is selected from the flight route library; and if the selected flight route satisfies a set condition, the airplane flies into the selected flight route. When the airplane flies into the selected flight route, a remote sensing device on the airplane is turned on. If the relationship between the real-time flight information of the airplane and the selected flight route does not satisfy the set condition, the airplane flies out of the route. When the airplane flies out of the selected flight route, the remote sensing device on the airplane is turned off. The method and the device can automatically select the flight route and automatically control on and off of the remote sensing device.