Background: Our hospital has been using Varian VitalBeam linear accelerator since December 2020. Daily quality control of accelerator beam stability in precision radiotherapy is very important. In this paper, we compare and analyze the beam stability of the accelerator with two monitoring methods. Objective: The long-term stability analyze and study of VitalBeam linear accelerator by using machine Machine Performance Check (MPC) and Morning Check. Methods: The energies of 6MV and 10MV x-ray most commonly used by Varian Linear accelerator (VitalBeam) for