MRI is an excellent non-invasive exploration method, for the reconstructed ligament image clarity and detailed with high resolution. The objective of the research is measurement of the anterior cruciate ligament (ACL) using MRI. Subjects and Methods: restrospectively study 40 cases native anterior cruciate ligament using MRI from October/2018 to June/2019, the research is measurement of the anterior cruciate ligament using MRI. Results: the average age is 31,75. Male prominent, right knee prominent too. In the sagittal plane, the average ACL length was 36,63 ± 2,15 mm; the average in males were 37,07 ± 2,10 mm; the average in females were 35,61 ±2,00 mm; 36,76 ± 2,21 mm in right knee; 36,39 ± 2,10 mm in left knee. In the sagittal plane, the average ACL width was 9,19 ± 1,84 mm; the average in males were 9,44 ± 1,85 mm; the average in females were 8,60 ±1,73 mm; 9,08 ± 2,00 mm in right knee; 9,40 ± 1,57 mm in left knee. Conclusion: the result of the research is the average ACL length and the average ACL width. They compared between left and right knees and between genders.