Objective To analyze the main reason of prolonged latency phase and the impact of prolonged latency phase on the delivery style. Methods The pregnant women with prolonged latency phase (n=92) and normal pregnant women (n=100) were retrospectively analyzed in the maternity department of the second affiliated hospital of Kunming medical college in 2007. Results There was no significant difference in the pelvis and fetal-pelvis in the two groups. The number of the pregnant women with fetal body weight (gt;4 000 g) in the prolonged latency phase group was obviously larger than that in the normal pregnant women group, with the significant difference. As to the situation of fetal position, there were more occipitoanterior positions and fewer occipitoposterior as well as occipitotransterse positions in the prolonged latency phase group (Plt;0.01). In the prolonged latency phase group, the pregnant women with normal delivery were fewer and the uterine-incision deliveries were more than those in the normal group, with the significant difference. Conclusion The prolonged latency phase prognosticates the incidence of dystocia. We should decide if the pregnant women have the tendency of prolonged latency phase before delivery and deal with it in time so as to prevent the occurrence of dystocia.