The invention relates to a steel plate surface polishing device, in particular to a steel plate surface polishing device for hardware machining. The steel plate surface polishing device for hardware machining aims to achieve the technical purposes that manual labor is not needed, the requirement for professional operation skills is not high, operation is easy, the price-performance ratio is high, the safety coefficient is high, and harm of the operation environment to health of operators is small. In order to achieve the technical purposes, the steel plate surface polishing device for hardware machining comprises a bottom plate, a first sliding rail, a first sliding block, a collection tank, a fixing stop block, a spring, a supporting rod, a first bearing pedestal, a first air cylinder, a disc and the like, wherein the first sliding rail is arranged in the middle of the top of the bottom plate. Through ingenious cooperation of the components, the effects that manual labor is not needed, the requirement for professional operation skills is not high, operation is easy, the price-performance ratio is high, the safety coefficient is high, and harm of the operation environment to health of the operators is small are achieved.