Fused quartz glass is widely used in aerospace, microoptical components, military and other fields because of its high heat resistance, low thermal expansion coefficient, good insulation properties, and so on. Higher requirements are put forward for its machining precision and surface quality. Because femtosecond laser has the characteristic of "cold processing", it has shown unique advantages in the micro-nano processing of fused quartz glass. Fused quartz glass was processed by femtosecond laser with wavelength of 1030nm, repetition frequency of 100kHz and pulse width of 290fs. The damage threshold of fused quartz glass under different objective lenses was determined. The effects of laser power, scanning speed, defocus and scanning times under different objective lenses on the machining line groove were studied. With the method of layer-by-layer superposition machining, the groove with the ratio of height to width (4∶1) was obtained at low power, and the width and depth of the groove were improved, and the micro-nano machining could be carried out on the thinner fused quartz glass (200μm).