Objective To investigate the expression and clinical significance of serum PTX3 in HCC patients. Methods We selected 78 HCC patients as the liver cancer group, and 78 cases of healthy subjects as the healthy control group. The PTX3 levels were detected and compared between the two groups. The differences of PTX3 levels in patients with different pathological characteristics were analyzed. ROC curve was used to analyze the auxiliary diagnostic value of serum PTX3 in HCC. Results PTX3 level in HCC patients was higher than that in healthy control group (P < 0.05). PTX3 level in stage Ⅰ group was higher than those in the stage Ⅱ group and Ⅲ group (P < 0.05). PTX3 level in patients with tumor ≥5cm was significantly lower than that with tumor diameter < 5cm (P < 0.05). In addition, PTX3 level in patients with HBV infection was significantly higher than that without HBV infection (P < 0.05). The AUC was 0.938. Conclusion The serum PTX3 level is significantly increased in patients with HCC. It has auxiliary diagnostic value for HCC.