Lifting speed control system in VAD method

The invention provides a lifting speed control system in a VAD method, and aims to solve the technical problem that the uniformity of a preform rod is poor due to the fact that the spraying amount of raw materials and the amount of soot are difficult to control. The control system comprises a starting rod and a blow lamp located on one side of the bottom of the starting rod, and further comprises a first-stage supporting assembly, a second-stage supporting assembly and a third-stage supporting assembly, one end of the connecting piece is hinged with the other end of the balance lever; the second-stage supporting assembly is located below the blow lamp and comprises a labor-consuming lever with one end hinged to the other end of the connecting piece; wherein the other end of the labor-consuming lever is hinged with the bottom of the blowtorch, a power arm and a resistance arm of the balance lever are equal in length, the ratio of the length of the power arm of the labor-consuming lever to the length of the res