Method and system for cyclic utilization of materials during production of polycrystalline silicon

The invention discloses a method and system for cyclic utilization of materials during production of polycrystalline silicon. The method comprises the steps of (1) performing reduction reaction on trichlorosilane and hydrogen to obtain polycrystalline silicon and reduction tail gas; (2) performing dust removal treatment on the reduction tail gas to obtain reduction tail gas subjected to dust removal; (3) performing compression cooling treatment on the reduction tail gas subjected to dust removal so as to separate first chlorosilane and compressed gas from the reduction tail gas; (4) performing distillation and purification on first chlorosilane to obtain residual liquid, trichlorosilane, dichlorosilane and silicon tetrachloride; (5) returning trichlorosilane obtained in the step (4) to the step (1) to perform reduction reaction, and performing hydrogenation reaction between one part of silicon tetrachloride and silicon powder and hydrogen so as to obtain second chlorosilane; (6) performing reverse disproportionation reaction between one part of silicon tetrachloride and dichlorosilane so as to obtain third chlorosilane; (7) returning second chlorosilane and third chlorosilane to the step (4) to perform distillation and purification.