Combustion characteristic in growth chamber for preparation of single crystal with hydro-oxygen flame fusion method was investigated. The results show that along the centerline of growth chamber a peak temperature 3504.3 K could be reached when the flow rates of oxygen and hydrogen were 6 L/min and 20 L/min respectively. With the increasing hydrogen flow rate, the temperature of the center and the diameter of the central flame increased gradually in the chamber. With the increasing oxygen flow rate, the position of the peak temperature gradually moved down, which downward moved 5 mm when the central oxygen flow rate increased for 1 L/min, while the average temperature rose 230℃ at a distance 110 mm to the nozzle. The diameter of hydrogen distribution circle had little effect on the center and radial temperature distributions, the central oxygen impact and the ignition position of the flame. As a result, the optimal position for single crystal growth could be easily acquired for the preset flow rates of the two gases and .