To investigate the therapeutic effect of conversion therapy and its correlation with vascular endothelial growth factor (VEGF) expression in unresectable rectal cancer with liver metastasis. A total of 116 cases of unresectable rectal cancer patients with liver metastasis were randomly divided into control and observation group, 58 cases in each group, all of these patients were treated by conversion therapy, patients in control were treated by FOLFOXIRI treatment program, and in observation group were treated by FOLFOXIRI program treatment and bevacizumab. Efficacy and adverse reactions were compared between the two groups, the levels of VEGF in portal vein and the expression of VEGF in cancer tissue were compared, after 5 years of follow-up, the prognosis of the two groups were observed. Objective efficiency and conversion rate of observation was significantly higher than the control group, survival rate of postoperative observation was significantly higher than that of control group (P>0.05). There was no significant difference in adverse reactions between the two groups (P>0.05). The positive rate of VEGF in portal vein blood and the expression of VEGF in the observation was significantly lower than that in the control group (P<0.05). The 5-year survival rate of VEGF high expression was significantly lower than that of VEGF low expression group (P<0.05). FOLFOXIRI combined with bevacizumab in patients with unresectable hepatic metastasis of rectal cancer can provide higher conversion rate and hepatectomy opportunities, and reduce VEGF expression in patients with unresectable rectal cancer, which is closely related to VEGF expression, therefore it is beneficial to better local control and to improve long-term survival.