The invention discloses a process for preparing dichloropropanol by an autocatalytic reaction of glycerol and hydrogen chloride. The process comprises the following steps: the glycerol and the hydrogen chloride gas perform the autocatalytic reaction at the temperature of between 105 and 160 DEG C and pressure of between 0.05 and 0.5MPa, and generated water is distilled and removed during the reaction. The invention also discloses a system for preparing the dichloropropanol by the autocatalytic reaction of the glycerol and the hydrogen chloride. The invention adopts the technology of the autocatalytic reaction of the glycerol and the hydrogen chloride without using a catalyst, so that the production cost is remarkably reduced, formation of high boiling side products is eliminated, and the reaction selectivity is improved. The invention has the advantages of simple process and low production cost. The system can ensure that the glycerol is completely converted and greatly improves the selectivity of the dichloropropanol, so that the purity of the finally prepared dichloropropanol is more than 99.5 percent.