The femtosecond pulse laser is a useful tool for micro/nano-machining, which is a fundamental technology for fabricating micro 3D structure devices or components such as micro fluidic devices or micro optical components. However, it is a challenge to control the machining precision since the laser is a non-contact tool and the machining result is affected by various factors. To figure out the influence of these factors, the a concept of named asof laser ablation volume (LAV) is introduced in the thesis research work to describe the ‘shape’ of the laser machining tool. The spatial structure of LAV is investigated to provide the principle to about controling the resolution and the depth evolution in a micro machining process. The shape and the size of LAV are determined by the pre-designed parameters. A computational model based on the shape of LAV has been verified to deal with different combinations of the moving path and moving speed of LAV for the purpose to improve the machining accuracy. Furthermore, based on the concept of LAV, a closed loop control of the micro milling process has been successfully accomplished in which the laser triggered plasma is employed as a real-time feedback indicator.