Abstract： Objective To study the detection and clinical signitlcanee of C reactivn protein(ClIP)and P-seleetin(P-sel)in patients with ulcerative colitis(UC).Methods The levels of peripheral blood ClIP and P-sel in patients with UC(n=53)and normal control group(n=35)were detected and the effects on disease severity were analyzed subsequently.Results The levels of blood CRP and P-sel in active phase group were significantly higher than those in catabasis group and normal controls group(P＜0.05);severe stage and medium stage were signiticandy higher than those in mild stage(P＜0.05,P＜0.01),severe stage was significantly higher than those in medium stage(P＜0.05);the blood level of CRP was positively related to P-sel in active phase group(r=0.638,P＜0.01).Conclusion CRP and P-sel were correlated with invasion and severity of UC.