Abstract: Due to their simple structure, reliable operation and high efficiency, linear compressors are widely used in the research of miniature cryocoolers.The piston displacement is a significant indicator to monitor the output PV work provided by the compressor. This paper summarizes the existing methods to measure the piston motion displacement applied for linear compressors, including four direct measurement methods using LVDT, capacitance displacement transducer, strain gauge and laser displacement transducer, as well as two indirect measurement methods by pressure fluctuation or acceleration. The measuring principles are briefly illustrated, and the applications, advantages and disadvantages of various measurement methods are compared.This work provides a certain reference for the selection of piston displacement measurement methods for linear compressors.