A machining device based on a non-Newtonian fluid shear thickening mechanism polishing method comprises a workbench, a polishing tool system, an abrasive fluid circulation device and a computer control module, wherein the polishing tool system is installed on a portal frame of the workbench, an inlet of the abrasive fluid circulation device is communicated with an abrasive backflow opening in the workbench, and the workbench, the polishing tool system and the abrasive fluid circulation device are respectively connected with the computer control module. The machining device has the advantages that the application range is wide, the size of machined workpieces is not limited, the structure of the device is simple, the device is controlled easily, a computer controls the operation track of the device, the polishing process of non-Newtonian fluid abrasive fluid and the surfaces of the workpieces can be controlled effectively, a non-Newtonian fluid abrasive fluid circulation system is adopted, and the functions of removing abrasive dust, purifying, recycling, transporting and storing the abrasive fluid, and adjusting performance are achieved.