Objective To study the relation between premature rupture of membrans(PROM) and dystocia and its treatment. Methods 200 cases of lying-in women without pregnant complitions were analyzed,including 200 cases of PROM,200 cases of not-PROM as control,so as to know the rate of dystocia. Results The rate of dystocia of PROM and not-PROM were 39% and 20%.There was significant difference between PROM and not-PROM. Conclusion PROM often indicates occurrence of dystocia and should be paid more attention.