The invention relates to a hydrogen recovery method in the exhaust generated by producing polysilicon. The exhaust mainly comprises hydrogen, chlorine hydride, dichlorosilane, trichlorosilane and tetrachlorosilane. The method comprises the following steps: pressurizing and cooling the exhaust in order to turn trichlorosilane and tetrachlorosilane to liquid state while hydrogen, chlorine hydride and dichlorosilane still being gas state, so that the gas hydrogen, chlorine hydride and dichlorosilane can be separated from the liquid trichlorosilane and tetrachlorosilane by gas liquid separation; dissolving the gas chlorine hydride and dichlorosilane into the liquid tetrachlorosilane by passing gas hydrogen, chlorine hydride and dichlorosilane through the liquid tetrachlorosilane, so that separating the hydrogen from chlorine hydride and dichlorosilane. The invention recovers the hydrogen in the exhaust by dry treatment and the hydrogen can be reused in the polysilicon production, which makes good use of the material, reduces pollutants, settles the problem of environmental pollution, improves the product quality and reduces the cost.