To identify how influence preoperative predictable factors for knee function after one year of anterior cruciate ligament reconstruction (ACLR). The purpose of this study is to investigate the relationship of preoperative quadriceps strength and post-operative knee function scores (Lysholm score and International Knee Documentation Committee [IKDC] score) after surgery. We extracted seventy-one subjects who underwent hamstring autograft reconstruction to evaluate randomly. Muscle strength deficits were measured with CSMI isokinetic dynamometer. One year after ACLR, we collected these scores from subjects completed. After identification of baseline independent variables between quadriceps muscle strength deficits and both Lysholm score and IKDC score, we examined that how relevant influence in these relationship with these factors by classifying quartile groups. We demonstrated that quadriceps muscles strength and knee function scores were identified as significant correlation. It was compared with quartile outcome in order to analyze that how different result comes out as a degree of deficit. As a result, the only Q1 group who indicated less quadriceps muscle strength deficit (within 23% deficits) effected to knee function scores after one year surgery. The less of quadriceps muscle strength deficit indicated before surgery, the better functional knee score level turns up. Therefore, the result verified that there are significantly positive influences between these relationships after one year of ACLR.