Objective: To study the effects of ulinastatin on the early postoperative cognitive function and brain injury in adult cardiac surgery. Methods: The randomized controlled trials on the effects of ulinastatin on the early postoperative cognitive function and brain damage of adult cardiac surgery published from January 2015 to January 2020 in China HowNet, Wanfang database, Vip database, the National Medical Library Biomedical Information Retrieval System (PubMed), Cochrane Library, etc. were searched. The literatures were screened according to the inclusion and exclusion criteria, the data were extracted and summarized. Meta-analysis was carried out by RevMan5.3 software. Results: A total of 8 articles were finally included, involving 493 patients. Taking ulinastatin as an experimental group and normal saline as a control group, Meta-analysis showed that the mental state examination scale score of the experimental group was higher than that of the control group at 3 d and 7 d postoperatively (P<0.05); after 30 min and 6 h, the plasma S-100β protein and neuron-specific enolase levels in the experimental group were lower than those in the control group (P<0.05); at postoperation 3 h, and 12 h, the interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) in the experimental group level were lower than those in the control group (P<0.05). Conclusion: The effect of ulinastatin in perioperative period of cardiac surgery patients is ideal, which can improve early postoperative cognitive function and reduce brain injury.