One of the main and primarily phase to success of radiotherapy is accurately localization of the target volume and health peripheral tissues by radiotherapy simulator. The aim of this study is to investigate the some specific quality control tests necessary to provide adequate confidence of radiotherapy simulator performance Various essential parameters for quality control of Acuity- Varian radiotherapy simulator such as matching of mechanical measurements and electrical readouts, isocenter check, Congruence between optical field and radiation field, laser positioning system, kVp accuracy of X-ray beam, flat panel performance (resolution and low contrast sensitivity), etc were checked by quality control test tools. All investigated tests for matching of mechanical measurements and electrical readouts of field size, rotation and movement of table, gantry and flat panel detector were within the tolerance limits. The accuracy and reproducibility of KV passed the acceptable values. All the lasers were aligned with isocenter. However resolution of flat panel was within tolerance limit but low contrast sensitivity was not passed. The various quality control tests carried out on Acuity-Varian radiotherapy simulator were within recommended limits except the low contrast sensitivity that is in borderline of tolerance.