The invention discloses a preparation technology of a carbon / carbon composite material crucible for a monocrystalline silicon furnace, and the preparation technology comprises the following steps of: adopting a polyacrylonitrile nitrile base carbon fiber-woven performing body, taking mixed gas of natural gas, propylene, liquefied petroleum as a carbon source and nitrogen or argon as carrier gas, in a uniform temperature thermal field formed by a vertical pot type deposition furnace, timely switching the upper gas charging and lower gas charging of a pipeline, due to the pressure difference of the gas inside and outside the crucible, and in combination with a uniform temperature method, a differential-pressure method and a compulsive gas current method, realizing the quick densifying of the whole crucible blank body, wherein after 300-350 hours, the intensity of the crucible can reach to more than 1.6g / cm<3>, compared with the conventional free deposition technology, the preparation technology can be used for greatly shortening the deposition time, and reduces the production cost. After being mechanically machined, the crucible is used for a thermal field of the monocrystalline silicon furnace, compared with the hot isostatic pressure graphite crucible, the carbon / carbon composite material crucible has the advantages that the service life is prolonged by 3-5 times, the cost performance is obviously better than that of the graphite crucible, and the production cost and labor intensity of the monocrystalline silicon are greatly reduced.