Femtosecond (Fs) laser micromachining is the most effective and flexible method for edge-cutting or transforming the physical properties of various crystalline brittle materials. Fs-laser micro-machining produces slag on the residual surface of micro-structures that reduces the quality and processing efficiency of a machined residual surface. In order to overcome the challenges overlaid during the processing of brittle materials, Fs-laser assisted ultrasonic nitrogen jet micro-machining technique is proposed. The method was applied to quartz chips to investigate improvements in surface quality after laser processing. For conceptualizations, an ultrasonic nitrogen nozzle based on a piezoelectric transducer was designed and Finite Element Method (FEM) was employed to realize the transition of a flow field. An experiment was performed that differentiate the quality of micro-grooves into quartz chips, and the results promote the significance of Fs-laser-assisted ultrasonic nitrogen jet micromachining for the processing of brittle materials. Besides, the machining quality at residual surfaces of quartz chips after laser processing was substantially improved. The process provides an aid to break down the slag into further tiny nano-particles and prevent a recast layer, meanwhile, it enhances the surface quality and processing efficiency without implementing any extensive procedure.