An unmanned aerial vehicle, comprising: an unmanned aerial vehicle body comprising an airframe and an articles storing device disposed behind the airframe and configured to store a variable weight part; at least two front arms symmetrically arranged with respect to a central axis of the airframe along a front-rear direction and at least two rear arms symmetrically arranged with respect to the central axis of the airframe; preferably, each of the front arms and the rear arms is formed to be a linear shape or an arc shape; preferably, two front arms and two rear arms are provided, and an included angle between the two front arms is larger than an included angle between the two rear arms; preferably, a length of the rear arm is larger than a length of the front arm; rotor-wing electric motors comprising at least two front electric motors and at least two rear electric motors; wherein a first end of each of the front arms is connected with a front end of the airframe, and a second end of each of the front arms is provided with a front electric motor to drive the unmanned aerial vehicle; a first end of each of the rear arms is connected with a rear end of the airframe, and a second end of each of the rear arms is provided with a rear electric motor to drive the unmanned aerial vehicle; wherein an acting point of a resultant force from the front electric motors and the rear electric motors exerted on the unmanned aerial vehicle is the lift force center, and a gravity center of the unmanned aerial vehicle is adjacent to the lift force center, a projection of the lift force center on a horizontal plane is configured to be adjacent to a projection of a gravity center of the variable weight part on the horizontal plane, a projection of an intersection region bounded by extension lines of the rear arms towards the airframe and extension lines of the front arms towards the airframe on the horizontal plane is located in front of a projection of a lift force center of the unmanned aerial vehicle on the horizontal plane, characterized in that a heat dissipation waterproof cover is disposed to an upper end face of the rotor-wing electric motors, the heat dissipation waterproof cover comprises an upper sealing surface and a sidewall circumferential surface, the sidewall circumferential surface is provided with a certain number of ventilation holes adjacent to the upper sealing surface, and a blade distant from a center of the heat dissipation waterproof cover is disposed in the heat dissipation waterproof cover and extends from the ventilation hole towards a center of an inner wall of the upper sealing surface. an unmanned aerial vehicle body comprising an airframe and an articles storing device disposed behind the airframe and configured to store a variable weight part; at least two front arms symmetrically arranged with respect to a central axis of the airframe along a front-rear direction and at least two rear arms symmetrically arranged with respect to the central axis of the airframe; preferably, each of the front arms and the rear arms is formed to be a linear shape or an arc shape; preferably, two front arms and two rear arms are provided, and an included angle between the two front arms is larger than an included angle between the two rear arms; preferably, a length of the rear arm is larger than a length of the front arm; rotor-wing electric motors comprising at least two front electric motors and at least two rear electric motors; wherein a first end of each of the front arms is connected with a front end of the airframe, and a second end of each of the front arms is provided with a front electric motor to drive the unmanned aerial vehicle; a first end of each of the rear arms is connected with a rear end of the airframe, and a second end of each of the rear arms is provided with a rear electric motor to drive the unmanned aerial vehicle; wherein an acting point of a resultant force from the front electric motors and the rear electric motors exerted on the unmanned aerial vehicle is the lift force center, and a gravity center of the unmanned aerial vehicle is adjacent to the lift force center, a projection of the lift force center on a horizontal plane is configured to be adjacent to a projection of a gravity center of the variable weight part on the horizontal plane, a projection of an intersection region bounded by extension lines of the rear arms towards the airframe and extension lines of the front arms towards the airframe on the horizontal plane is located in front of a projection of a lift force center of the unmanned aerial vehicle on the horizontal plane, characterized in that a heat dissipation waterproof cover is disposed to an upper end face of the rotor-wing electric motors, the heat dissipation waterproof cover comprises an upper sealing surface and a sidewall circumferential surface, the sidewall circumferential surface is provided with a certain number of ventilation holes adjacent to the upper sealing surface, and a blade distant from a center of the heat dissipation waterproof cover is disposed in the heat dissipation waterproof cover and extends from the ventilation hole towards a center of an inner wall of the upper sealing surface.