A rotor assembly includes a propeller, a motor, and a connection assembly. The motor includes a stator and a rotator rotatable with respect to the stator. The connection assembly is configured to connect the propeller to the motor and includes a locking member that is arranged between the propeller and the motor. The locking member is configured to rotate with respect to the rotator and the propeller in a rotation direction identical to a rotation direction of the propeller in operation to lock the propeller to the motor.