Objective: To study the first aid effect of ulinastatin in treatment of acute paraquat poisoning and its influence on the serum interleukin-18(IL-18), matrix metalloproteinase-9(MMP-9) and high mobility group protein B1(HMGB1) levels, biochemical index and blood gas index. Methods: 80 patients of chronic renal failure who received therapy from January 2016 to January 2019 in our hospital were selected, according to random number table, they were divided into the observation group and the control group, each group had 40 cases. The control group was given routine treatment, while the observation group was treated with ulinastatin on the basis of the control group. The serum levels of IL-18, MMP-9, HMGB1, biochemical indexes, blood gas analysis, 28-day complications and mortality were compared between the two groups. Results: After treatment 7 days, the serum IL-18, MMP-9, HMGB1, alanine aminotransferase(ALT), creatinine(Cr), creatine kinase isoenzymes(CK-MB), partial pressure of carbon dioxide(PaCO2) in the observation group were significantly lower than those in the control group, and partial pressure of oxygen(PaO2) in blood was significantly higher than those in the control group, the differences were statistically significant(P<0.05); the 28-day pulmonary failure, renal failure, toxic myocarditis, multiple organ dysfunction syndrome(MODS) and mortality rate in the observation group were significantly lower than those in the control group, the differences were statistically significant(P<0.05). Conclusion: Ulinastatin has a remarkable first aid effect on acute paraquat poisoning, and can alleviate the tissues and organs inflammation damage caused by serum IL-18, MMP-9 and HMGB1,improve biochemical index and blood gas indicators, and reduce the incidence of organ injury and mortality, it’s worth popularizing. [ABSTRACT FROM AUTHOR]