Objective To investigate the clinical outcomes of autologous platelet rich plasma (PRP) for anterior cruciate ligament (ACL) reconstruction. Methods Between August 2014 and August 2016, 42 patients with ACL ruptures who underwent arthroscopic ACL reconstruction were randomly divided into 2 groups: 21 patients received graft soaked with PRP (trial group) and 21 patients received routine graft in ACL reconstruction (control group). Because 6 patients failed to be followed up, 17 patients of trial group and 19 of control group were enrolled in the study. There was no significant difference in gender, age, body mass index, side, injury reason, disease duration, Kellgren-Lawrence grade, and preoperative visual analogue scale (VAS), Lysholm score, and International Knee Documentation Committee (IKDC) activity scores between 2 groups (P>0.05). VAS score, Lysholm score, and IKDC activity scores were used to evaluate pain and function at 3 and 12 months postoperatively. Further, second arthroscopy and MRI examination were performed at 12 months postoperatively. Results The patients in both groups were followed up 3 to 12 months with an average of 9.83 months. The VAS score, Lysholm score, and IKDC activity scores were significantly improved at 3 and 12 months after operation in 2 groups (P<0.05), and the scores of trial group were significantly better than those of control group at 3 months (P<0.05), but no significant difference was found between 2 groups at 12 months (P>0.05). No complications of effusion, infection, and allergy were observed in 2 groups during follow-up. MRI showed good position of ACL grafts and good signal quality of the graft in the majority of the cases. However, mixed hyperintense and presence of synovial fluid at the femoral bone-tendon graft interface were found in 3 patients of trial group and 4 patients of control group, indicating poor remodeling ligamentation. MRI score was 3.53±1.13 in trial group and was 3.21±0.92 in control group, showing no significant difference (t=0.936,P=0.356). The second arthroscopy examination showed ligament remodeling score was higher in trial group than control group (t=3.248,P=0.014), but no significant difference was found in synovial coverage score and the incidence of cartilage repair (t=2.190,P=0.064;χ2=0.090,P=0.764). Conclusion PRP application in allograft ACL reconstruction can improve knee function and relieve pain after operation, which may also accelerate graft remodeling.