Objective To study the effect and adverse reaction of lactulose oral solution on the treatment of postpartum constipation.Methods A total of 120 patients with postpartum constipation were randomly divided into treatment group (n=61) and control group (n=59).The treatment group received 15 mL lactulose oral solution,twice a day.The control group received wheat cellulose particles 3.5 g,twice a day.After the improvement of symptoms,the patient''s medication frequency was changed to 1 time a day,the course of treatment was 2 weeks long.The curative effect(including before treatment,period during the treatment,and the first week after finish the whole treatment) and the recurrence of constipation after treatment were observed.Results The frequency of defecation per week in the treatment group was(3.83±1.61)times,that in the control group was(3.09±1.53)times at the first week after treatment(P<0.05),those were(6.22±1.96)and(5.15±1.71)times respectively in the second week(P<0.01),and (6.43±1.87),(5.29±1.64)times respectively at the first week after treatment(P<0.05).The total recurrence rate in the two groups were 4.92% and 10.17% respectively(P>0.05) after follow-up to 60 d.The degree of drug acceptance in two groups was 100.00% and 76.27% respectively(P<0.01).There was no obvious adverse reaction in both two groups.Conclusion The effect of lactulose oral solution on the treatment of postpartum constipation is definite and with low recurrence rate.Lactulose oral solution has a good taste,easily to be taken and to be accepted,it is worthy of clinical application.