The invention provides a method of increasing the content of silicon in lead-zinc tailings. The method comprises the following steps that firstly, the disposal of the lead-zinc tailings is conducted;secondly, the calcium and magnesium roughing operation is conducted; thirdly, the calcium and magnesium scavenging operation is conducted, specifically, the tailings which exist after the calcium andmagnesium roughing operation in the second step is accomplished are subjected to the calcium and magnesium scavenging operation for at least one time, 40g/t-50g/t calcium and magnesium collecting agent oleic acid is added to a floatation tank of the first-time calcium and magnesium scavenging operation, the ore concentrate which is obtained after the calcium and magnesium scavenging operation is accomplished returns to the floatation tank in the previous step, the tailings which exist after the calcium and magnesium scavenging operation is accomplished enter the next calcium and magnesium scavenging operation, products are separated, then the return step is repeated, and the tailings which are finally separated out enter the disposal process in the next step; and fourthly, the tailings which are finally separated out in the third step are subjected to concentration filter pressing operation and then can be reused. By the adoption of the method, the content of silicon dioxide in the lead-zinc tailings is effectively increased, the application value of the lead-zinc tailings is effectively improved, the application range of the lead-zinc tailings is broadened, the adjustment of the PH value and the usage of other component inhibitors are not required in the disposal process of the lead-zinc tailings, and the production cost, the storage stacking pressure and the occupied area areeffectively reduced.