Abstract: Abstract In this paper, testing method for spandex fatigue and runback of elastic warp knitted fabrics was studied. First influences and significances of initial elongation and reciprocating stretching on spandex fatigue and runback of elastic warp knitted fabrics were tested and analyzed. And then differences in spandex fatigue and runback of initial elongation and no initial elongation test were analyzed, combined with results of trying on shorts. The results show that fatigue is serious as the increase of initial elongation percentage and initial elongation percentage has significant influence on deformation rate and reversion rate and fatigue grade，that fatigue and runback are serious as the increase of reciprocating stretching percentage and reciprocating stretching percentage has significant influence on deformation rate and reversion rate and fatigue grade e and runback. Fatigue test results of no initial elongation conform to actual wearing, which initial elongation percentage is 60%，reciprocating stretching percentage is less than 80% the gauge length. The research results can provide a certain reference to fatigue and runback test for elastic warp knitted fabrics.