External displacement sensor

The invention relates to an external displacement sensor. The external displacement sensor is characterized by comprising a linear bearing, an outer sleeve, springs, a sliding guide rod, a displacement sensor measuring rod and a movable sleeve, wherein the displacement sensor measuring rod is located in the sliding guide rod, the sliding guide rod is located in the outer sleeve, the sliding guide rod and the outer sleeve are coaxially fixed through screws, an annular space which is used for containing the linear bearing is formed between the movable sleeve and the sliding guide rod, and the linear bearing is located in the annular space; and the springs are fixed in an internal hole of the outer sleeve through spring seats, retaining rings are mounted at the left end of the movable sleeve, the spring seats are mounted between the movable sleeve and the outer sleeve, the movable sleeve is provided with a sealing cover at the end part of the outer sleeve, an O-shaped sealing ring is arranged between the sealing