Abstract: The Microwave Plasma Chemical Vapor Deposition（MPCVD） system has emerged as a highly efficient method for producing high-quality diamond films, which have a wide range of applications in electronics, optics, and cutting tools. However, traditional MPCVD systems operating at a frequency of 2.45 GHz face inherent limitations regarding the diameter of the film area that can be deposited. Typically, this diameter ranges from 50 to 70 mm, constraining the potential for large-area applications. To address this challenge, recent efforts have focused on optimizing the design of the cavity dimensions within the MPCVD system. By simulating and analyzing the microwave electric field, researchers have been able to identify configurations that enhance the deposition area for diamond films. These optimizations are critical for increasing the uniformity and quality of the deposited films, allowing for more versatile industrial applications. In addition to cavity design improvements, numerical simulations have been conducted to investigate the distribution characteristics of electron density and temperature within the plasma. Achieving a uniform plasma distribution on the deposition substrate is vital for enhancing the overall film quality and expanding the deposition diameter. Through these simulations, researchers have successfully demonstrated that the deposition diameter can be increased to 90 mm, significantly surpassing the limitations of traditional systems. The simulation results reveal that when the microwave source power is set to 6 000 W and the pressure within the cavity is maintained at 14.7 kPa, a high-density and uniform plasma is generated on the deposition substrate. Specifically, the electron density reaches an impressive value of 1.76×10¹⁸ m⁻³, while the temperature of the plasma is approximately 4.7×10⁴ K. These findings indicate that the optimized MPCVD system can produce high-quality diamond films over a larger area, paving the way for advancements in various technological fields. The enhancements achieved through careful simulation and design highlight the potential for further developments in plasma deposition techniques.