In order to overcome the negative influence of elasticity coefficient changeability of force- transmitting medium and directional movement of sliding block on the measurement accuracy of existing fiber Bragg grating (FBG) displacement sensors, a novel sliding type FBG displacement sensor was investigated. Special design and measures were adopted, including perpendicular sliding surface to the constrain face of sliding block, constant-strength beam with altered cross-section, and circular sliding surface of the beam, which enable the sensor to possess anti-interference of directional sliding, high sensitive measurement to beam deflection, and abrasion performance in reciprocating displacement measurement in long-term. The measuring principle of the sensor was deduced and a sensor prototype was manufactured for performance testing. Experimental results demonstrate that displacement sensitivity of the sensor is 20.11 pm/mm in the range of 0—100 mm, and the measuring accuracy is 0.999 5%F.S, which indicate that the sensor is a promising candidate for micro displacement measurement. Moreover the repeatability error and hysteresis error are only 0705% and 0.403% respectively, which demonstrates good creep resistance of the sensor. These excellent performances can satisfy the requirements of high precision and long term stability in structural health monitoring of machinery equipment and civil engineering.