The invention relates to a growth method of bismuth silicate (Bi12 SiO20, BSO for short) monocrystal with a hydrothermal method. The method is characterized in that crystal growth is executed by taking a fluoride mineralizer system. The method comprises the following steps: taking BSO raw materials as cultivation materials; putting the cultivation materials at the bottom of a golden lining sleeve;putting a golden baffle plate with 7-10% of aperture ratio at the middle lower part of the golden lining sleeve; separating a cultivation materials dissolving region at a lower part from a crystal growing region at an upper part; hanging seed crystal or gold wire at the top of the golden lining sleeve; adding fluoride solution with 0.3-6 mol/L of fluorine ion concentration into the golden liningsleeve according to 65-75% of filling degree; sealing the golden lining sleeve; putting the golden lining sleeve into a high pressure kettle; adding a certain quantity of deionized water or distilledwater into an interlayer between the golden lining sleeve and the high pressure kettle; sealing; heating; making the average temperature of the dissolving region be 365-420 DEG C and the average temperature of the growing region be 335-385 DEG C; and growing with constant temperature for 10-90 days to obtain the BSO monocrystal.