The invention discloses a treatment method of a polyhalite ore dissolution production fluid. The method includes a step of mixing the dissolution production fluid with production raw brine to obtain raw material brine which can be used for producing sodium chloride, potassium chloride, magnesium sulfate and/or carnallite. The dissolution production fluid is the brine which is obtained through a dissolution production process of polyhalite ore. The method omits a step of new-building a salt field, wherein the dissolution production fluid is fed into a production salt field with the raw brine together to generate salt under sun in the salt field. The method reduces production cost, reduces technical process and reduces production period, increases sources of production raw materials and increases utilization rate of the dissolution production fluid.