The accuracy of the equivalent length of plastic hinge directly affects the displacement capacity in the ductile design, which is critical to assess the seismic performance of the pier. The formula of the effective length of a plastic hinge in the current codes are mostly based on the test results of solid-section columns. Due to the obvious difference in performances of hollow and solid piers, the applicability of these formulations to hollow-section piers calls for further research. Seven specimens with different design parameters were tested by semi-static loading, as well as the damage evolution and developing tendency of the plastic region were investigateds. The influences of shear span ratio, longitudinal reinforcement and stirrup ratio were studied to find out their effects on the distribution of plastic hinge of hollow piers. Through comparison between the equations and the test results, it can be found that the length of a plastic hinge increases with the  calculated length of a column. The stirrup and longitudinal reinforcement ratio also have influence to some extent. Among all the existing codes, the value based on Eurocode8 is consistent with the measured length of plastic hinge. Then formulations of Eurocode8, Telemachos and Gao are suggested for determination of the plastic deformation capacity of a rectangular hollow-section pier because the equivalent length of plastic hinge is very close to the test data.