Inclusion Criteria:  postpartum : ≥ 3 months pregnancy-related pelvic pain pain location is located between posterior iliac crest and gluteal fold Clinical screening test for pelvic pain: ASLR : positive and SI joint ≥ 2 (+ symphysis ≥ 1)  Exclusion Criteria:  lumbar or pelvic surgery lother causes of pelvic pain (such as fractures) lRadiculopathy lother health problems, such as cancer, cardiovascular disease, rheumatism , etc ldaily activities limited , unable to complete the experiment lcommunication disorders lmental disorder lpregnancy lhave been trained in stable muscle strength in the past.