The invention relates to a system for measuring the surface topography of an aerospace thin-wall disc part and machining a fixture based on a digital signal processor (DSP). The system consists of a TMS320C6747 chip, and a DSP development board, a DSP development board 5V power supply, a quick servo tool rest, a piezoelectric ceramic displacement driver, a piezoelectric ceramic power amplifier, a capacitive sensor measuring head, a capacitive sensor signal amplifier, a capacitive sensor power supply, an absolute encoder, a linear grating ruler, a laser displacement sensor measuring head, a laser displacement sensor measuring head retainer, a laser displacement sensor controller, a laser displacement sensor power supply, an absolute encoder bracket, an elastic coupling, a monocrystalline diamond turning tool, a thin-wall workpiece, a fixture mounting platform and an experiment platform which are based on the chip. The system has the functions of quickly measuring the surface topography and manufacturing the fixture at high accuracy, has practical value in the field of machining, and can solve the problems that the deformation of the thin-wall part is large, new deformation is generated in each machining process, accuracy is difficult to ensure, and the fixture cannot meet the clamping requirement in each process.