To investigate the clinical efficacy of arthroscopic measurement of intra-articular graft length in the application of total internal reconstruction of the anterior cruciate ligament(ACL). The 60 patients with ACL injury treated between January 2020 and January 2022 were retrospectively analyzed. There were 37 males and 23 females, aged from 22 to 44 years. According to the different surgical methods, they were divided into two groups:conventional surgery group (conventional group) and pull-line measurement group (measurement group), with 30 cases in each group. In the conventional group, there were 20 males and 10 females, with an average age of (30.00±3.95) years old;the body mass index (BMI) was (22.58±1.41) kg·m-2;there were 9 cases on the left side and 21 cases on the right side;the time from injury to operation was (3. 00±1.35) days. In the measurement group, there were 17 males and 13 females, with an average of(32.00±4.29) years;BMI was (23.29±1.39) kg·m-2;there were 12 cases on the left side and 18 cases on the right side;the time from injury to operation was (3.00±1.27) days. The clinical data of the patients before surgery, 6 months after surgery and 12 months after surgery were collected and recorded. The clinical efficacy of the two methods was compared in terms of postoperative VAS, KOOS, Lysholm score, IKDC score, knee stability (Lachman test, anterior drawer test and axial shift test), the degree of widening of bone tunnel diameter measured by CT at different stages of the postoperative period and MRI scoring system. At 12 months after surgery, the VAS of the measurement group was lower than that of the conventional group(P<0.001). At 12 months after surgery, KOOS scores in the measurement group were higher than those in the conventional group, and there were statistically significant differences in all scores except symptom scores (P<0.05). Six months after operation, Lysholm total score and IKDC total score in the measurement group were higher than those in the conventional group, and the difference was statistically significant (P<0.05). At 12 months after surgery, knee stability tests were performed, and the differences between the Lachman test, anterior drawer test and axial shift test measurement group and the conventional group were not statistically significant (P>0.05). However, overall knee instability analysis showed that the knee stability of the measurement group was better than that of the control group, and the difference between the groups was statistically significant (P=0.038). The imaging assessment of patients in both groups at 6 months after surgery showed that the widening of tendon tunnel diameter in both femur and tibia was reduced in the measurement group compared with the conventional group after surgery, and the difference was statistically significant(P<0.05);MRI scores were higher in all patients in the measurement group those in the conventional group, at 6 months and 12 months agter surgery(P<0.05). Arthroscopic measurement of intra-articular cavity graft length in total internal technique for ACL reconstruction, high tendon utilization, good stability, the knee joint function has recovered satisfactorily within one year, and the therapeutic effect is affirmed.