Muscle fatigue can be an effective factor in the occurrence of sports injuries. The aim of this study was to investigate the effect of acute lower limb fatigue on three-dimensional pelvic kinematics and lumbar curvature during unanticipated block among adolescent female volleyball players. In this semi-experimental study, given the inclusion criteria, 16 adolescent female volleyball players were selected through a convenience sampling method. In the pre-test phase, the lumbar curvature of the participants was measured by a flexible ruler, and then each subject performed three unanticipated single leg jump-landing maneuvers and the data was recorded by a motion analysis device. Then the intervention of volleyball-specific lower-limb fatigue protocol was applied and the players were re-evaluated. The Shapiro-Wilk test was used to check the homogeneity of variances, the dependent t-test was used to analyze the data, and MATLAB software used to analyze the kinematic data. The results represented, a significant difference in the increase of anterior tilt and external rotation of the pelvic at the initial contact and the decrease of anterior tilt and increase internal rotation of the pelvic at the peak of landing after applying the fatigue protocol (P≤0.05). However, no significant difference was observed in other kinematic variables (P≥0.05). According to the results, it seems that the kinematic changes observed after applying the lower limb fatigue protocol can increase the risk of anterior cruciate ligament injury in volleyball players.