Objective To observe and compare the effect of one -time root canal therapy and routine root canal therapy applied in acute pulpitis treatment.Methods 450 cases of patients with acute pulpitis treated by author were selected with 450 teeth involved,and were divided into one -time group and routine group by using the principle of random.Each of the groups included 225 cases of patients,with 225 teeth involved.One -time root canal therapy was given in one -time group,while routine root canal therapy given in routine group.Short -term effects were com-pared 1 week after therapy,while long -term effects were compared 1 year after therapy.Results 1 week after thera-py,213 cases in one -time group were excellent,excellent rate was 94.67%,while 139 cases in routine was excel-lent,excellent rate 61.78%.And there was statistical difference between the two groups (χ2 =21.970,P <0.05). There were 214 cases in one -time group which were effective,and the total effective rate was 99.56%,and 225 cases in routine group were effective,with total effective rate of 100.00%,and there was no statistical difference between the two groups (χ2 =0.018,P >0.05).One year after therapy,211 cases in one -time group were successful,success rate was 93.78%,and 223 cases were effective,total effective rate 99.11%.217 cases in routine group were success-ful,success rate was 96.44%,and 224 cases were effective,with total effective rate of 99.56%.There were no statis-tical differences of success and effective rate between the two groups (χ2 =0.085,0.006,both P >0.05 ). Conclusion It is effective to apply one -time root canal therapy to treat acute pulpitis under strict indications,pain relieved,referral time reduced,operation difficulty decreased,compliance increased.And the long -term effect of one-time root canal therapy is the same as routine root canal therapy,and the short -term effect is better.It is worthy of clinical use.