Excessive tibiofemoral rotation in weight-bearing position may be associated with patellofemoral pain syndrome (PFPS). A previous literature suggested that “posterior X taping” method is effective for correcting the reduction of hip adduction and tibiofemoral rotation in weight bearing position. The purpose of this study was to determine the effects of posterior X taping on the angles of hip adduction, tibiofemoral rotation, grades of the forward-step-down (FSD) performance test, and intensity of knee pain when descending stair in patients with PFPS. We recruited patients with PFPS. The knee pain intensity during FSD was measured using visual analogue scale system (100 mm) under both no-tape and tape conditions. A three-dimensional motion analysis system was used to assess the kinematics of lower limb joints during FSD. In addition, scoring system of FSD performance test was used to assess the movement deviation of the trunk and lower limb and one-leg balance. Participants with PFPS showed reduced pain intensity (p = 0.001) and improved scores on FSD performance test (p = 0.002) with posterior X taping compared to the no-tape condition during FSD. No significant alterations changes were noted in three dimensional angles of the hip, knee and ankle joints, especially hip adduction and tibiofemoral rotation between conditions. Posterior X taping decreases knee pain and improves the scores on FSD performance test for patients with PFPS.