The invention discloses a device for controlling a
heating temperature field to purify and prepare
polycrystalline silicon. The furnace body is provided therein with a heat insulation plate, a coolingplate, a
crucible, a heating induction ring and a heat preservation tube. The heat preservation tube is provided therein with an upper
graphite heating ring, a middle
graphite heating ring and a lower
graphite heating ring, connection rings are arranged between the upper graphite heating ring and the middle graphite heating ring, and between the middle graphite heating ring and the lower graphiteheating ring, respectively, and the connection rings are made from a high temperature resistant material with heat conduction coefficient of 10-50 W / m.k. A purification process comprises the steps: introducing a cooling gas into a cooling plate; introducing an
inert gas into a furnace body, and meanwhile discharging through an
exhaust pipe provided at the top of the furnace body to ensure a certain
gas pressure existing in the furnace body; and controlling the upper graphite heating ring, the middle graphite heating ring, and the lower graphite heating ring to cool according to a certain procedure. The device and process for controlling
heating temperature field to purify and prepare
polycrystalline silicon facilitates the formation of a uniform
temperature gradient, being favorable for
crystal growth, and can effectively prevent the stepwise sudden change of a stepwise heat field from top down.