The invention discloses a test method for particle filtering efficiency of a thermal desorption liner tube. The test method includes the following steps: arranging the thermal desorption liner tube requiring filtering efficiency test into a thermal desorption device; adjusting the thermal desorption device into working status; injecting a certain volume of silicon dioxide microsphere solution dispersed in an organic solvent into the thermal desorption device through a micro-sample injector; collecting penetrated silicon dioxide microspheres with a pure liquid at the outlet of the thermal desorption device; detecting the concentration of the collected silicon dioxide microspheres with an evaporative light-scattering detector to obtain a peak area A; with a blank liner tube not filled with the filter medium, re-doing the operations above to obtain a peak area A0; and calculating the filtering efficiency of the thermal desorption liner tube to particles being x in particle size according to the following formula: (1-A/A0)*100%. The test method is reliable in result and is quick to carry out. The result can directly reflect the filtering efficiency of the thermal desorption liner tube filled with the filter medium.