The invention belongs to the technical field of aerospace servo systems, and particularly relates to an external integrated displacement sensor mounting mechanism adapting to an electromechanical actuator. The mechanism comprises a deep groove ball bearing, a first guide column, a resistor assembly, an electric brush assembly, a second guide column, a sliding block, a piston rod, a sealing ring and an anti-attrition ring, the deep groove ball bearing and the guide column are installed, and the electric brush assembly is installed between a displacement sensor sheet and the sliding block; brushwires of the electric brush assembly are in contact with the resistor assembly; a sliding block is installed in the displacement sensor and fixedly connected with the extending part of the guide column through a sealing ring, and the displacement sensor is integrally installed on a shell of the electromechanical actuator and can independently conduct adjustment and other operations. The mechanismcan be applied to various electromechanical actuators, the structural reliability and stability of the product are improved, and the cost is reduced while the environmental adaptability of the product is improved; and meanwhile, the mechanism can be popularized and applied to an electromechanical actuator with the mechanism, and the machining difficulty caused by the fact that a split type platedisplacement sensor needs to be installed on an actuator shell is reduced.