Objective To investigate the efficacy of salvianolic acid for injection (SAFI) in acute cerebral infarction and its effect on oxygen free radicals. Methods The patients with acute cerebral infarction were collected from February 2017 to November 2017. The control group (n=76) received routine treatment of cerebral infarction and the study group (n=67) additional SAFI (0.13g), both groups for 2 weeks. The two groups were compared before and after treatment in the respects of degree of neurological deficit, including National Institute of Health Stroke Scale (NIHSS) score, modified Rankin Scale (mRS) score, Barthel index (BI) and change of serum malondialdehyde(MDA) and superoxide dismutase(SOD). SPSS statistics 17.0 was used for statistical analysis. Depending on data type, data comparison was made using t test, rank-sum test,or χ² test. Results There was no significant difference in baseline data between the two groups before treatment (P>0.05). After treatment, the overall effective rate of the study group was significantly higher than that of the control group(89.55% vs 67.11%), the difference was statistically significant (χ²=43.64, P<0.01). After treatment, NIHSS score [1(1,2) vs 2(1,4) points], mRS score [1(1,2) vs 2(1,3) points], BI index [100(85,100) vs 90(76,100) points] and scores improvement rate[0.7(0.4,0.8) vs 0.3(0.1,0.5); 0.5(0.3,0.8) vs 0.3(0.0,0.5); -0.4(-0.6, -0.1) vs -0.1(-0.2,0.0)] of the study group were improved compared with the control group, the differences are statistically significant (P<0.01). After treatment, the MDA of the study group decreased compared with the control group [1.5(1,2) vs 2(1,3)nmol/ml], the difference was statistically significant (P<0.01). After treatment, SOD [145.8(131.3,160.8) vs 143.6(128.7,153.9)U/ml] did not increase significantly in the control group, the difference was not statistically significant (P>0.05); while SOD increased significantly after treatment in the study group, [162.1(139.3,188.4) vs 149.9(131.3,167.3)U/ml], and compared with the control group, SOD [162.1(139.3,188.4) vs 145.8(131.3,160.8)U/ml] were significantly higher in the study group, the differences were statistically significant (P<0.05, P<0.01). Conclusion SAFI can significantly improve the score of neurological deficit and the ability of daily life of patients with acute cerebral infarction.SAFI might play antioxidant roles and eliminate free radicals by decreasing MDA and increasing SOD activity, thereby improving clinical prognosis.