Objective To investigate the clinical effect of low molecular heparin combined with mesalazine in patients with active ulcerative colitis(UC).Methods 90 cases of patients with UC were randomly divided into three groups:A group,B group and C group,with 30 cases in each group.A group was given oral treatment with sulfasalazine enteric-coated tablets,B group was given oral treatment with mesalazine and C group was given low molecular heparin calcium combined with mesalazine (4100 iu,1 /d).The three groups were treated for 2 weeks. Coagulant function index such as activated partial prothrombin time (APTT),fibrinogen(FIB),platelet count(PLT), platelet maximum aggregation rate(PAG(Max)),D-dimer(D-D),C-reactive protein(CRP)were detected in the two groups before and after treatment of 7 and 14d.Mayo disease activity index score was also recorded before and after treatment of 7 and 14d.And the differences among three groups were compared.Results There were significant differences in APTT,FIB,PLT and PAG(Max)after 7d,14d treatment among A,B and C groups(7d:F value were 17.652,12.427,42.873,14.318 respectively;14d:F value were 43.804,139.172,51.932,79.440 respectively,all P value <0.05).APTT of C group after 7d,14d[(36.32 ±3.56)μg/mL,(40.15 ±4.24)μg/mL]were higher than B group[(32.14 ±2.86)μg/mL,(33.04 ±3.32)μg/mL]and A group [(31.82 ±3.36 )μg/mL,(32.15 ± 3.24)μg/mL];FIB of C group after 7d,14d[(4.07 ±0.41 )g/L,(3.14 ±0.28)g/L]were lower than B group [(4.47 ±0.40)g/L,(4.06 ±0.33)g/L]and A group[(4.58 ±0.44)g/L,(4.23 ±0.37)g/L];PLT of C group af-ter 7d,14d[(262.22 ±60.61)×109 /L,(201.38 ±49.42)×109 /L]were lower than B group[(296.34 ±63.51)× 109 /L,(253.25 ±55.47)×109 /L]and A group[(301.71 ±70.62)×109 /L,(262.05 ±64.11)×109 /L];PAG (Max)of C group after 7d,14d[(0.46 ±0.08),(0.30 ±0.05)]were lower than B group[(0.57 ±0.10),(0.46 ± 0.06)]and A group[(0.59 ±0.12),(0.51 ±0.08)].There were significant differences in CRP,D-D after 14d treatment among A,B and C groups(F value were 91.967,139.172 respectively,all P value <0.05).CRP of C group after 14d[(7.50 ±1.35)mg/L]were lower than B group[(10.80 ±1.37)mg/L]and A group[(12.12 ±1.64)mg/L];D-D of C group after 14d[(0.26 ±0.02)mg/L]were lower than B group[(0.47 ±0.03)mg/L]and A group[(0.51 ± 0.04)mg/L].There were significant differences in Mayo index score,△Mayo index score after 14d treatment among A,B and C groups (F value were 182.170,89.802 respectively,all P value <0.05).Mayo index score of C group after 14d(1.51 ±0.33)were lower than B group(2.93 ±0.46)and A group(3.42 ±0.63);.△Mayo index score of C group after 14d(5.67 ±1.60)were lower than B group(4.25 ±1.32)and A group(3.79 ±1.21);Pearson corre-lation analysis showed that △Mayo Mayo index score were positively correlated with PAG(Max)reduction△PAG (Max),△D-D,△CRP,△PTL(r value were 0.616,0.702,0.734,0.569,respectively,all P <0.05).Multiple step-wise linear regression analysis showed that △PAG(Max),△D-D,△CRP,△PTL were closely related to △Mayo Mayo index score(partial regression coefficient were 4.209,2.451,0.801 respectively;t value were 7.890,4.787, 2.201,respectively,all P <0.05).Conclusion The clinical effect of low molecular heparin combined with mesala-zine in patients with active ulcerative colitis is effective,and the method can significantly improve the inflammation in patients with UC and high coagulation state,improving the clinical symptoms is better than the single drug,and worth clinical recommendations.