Owing to the large photo energy, 157nm laser is considered as one of promising micro-fabrication tools. In this paper, a micromachining system based on the 157nm laser is introduced. 2D laser direct-writing and 3D micro-structuring experiments are carried out for silica glasses, fibers and diamond. For natural diamond, the ablation threshold by 157nm laser is about 2.0J/cm2. Material removal is dominantly due to photon-chemical effect for 157nm laser ablation. Effectiveness of using 157nm laser for 3D micromachining is clearly demonstrated.