Abstract: Single crystal diamonds were grown on small diamond abrasive particles which were employed as seed crystals using HFCVD method. The influence of many factors, such as the size and arrangement of hot filaments, the temperature field of substrate and the distribution of small diamond abrasive particles on the growth rate and quality of homoepitaxial single crystal diamonds were analyzed. Three-dimensional finite element models were developed to investigate the temperature field in the CVD reactor which made significant contributions to the growth of single crystal diamonds. Based on the temperature distribution measured by thermocouple fixed in CAD reactor, the simulation was validated and the optimum arrangement of seed crystals was established from the simulation results. Furthermore, the simulation model was altered to optimize the process parameters of HFCVD deposition, and an improved process of depositing single crystal diamonds with high efficiency and great crystal shape was obtained, which laid the foundation of developing a new process of depositing large single crystal diamonds. As while, the CVD homoepitaxial coating recovery suggested a new method to improve the grade of crystal shape by HPHT process.