Strontium titanate ceramics with the feature of soft and brittle is difficult to process by mechanical processing method, because this method can easily cause crack and scratch on the surface. Master oscillator power amplifier (MOPA) pulsed fiber laser is conducted to controlled fracture cutting strontium titanate ceramic substrate. The mechanism of laser controlled fracture cutting is revealed as follows. Firstly the grooves formed by laser ablation. The groove depth then increases with the increase of the scanning times. When the thermal stress reaches the fracture threshold value of the material, the crack extends along the stress groove until it is completely split. It is an adaptive splitting process without the subsequent breaking procedure. In addition, it is found that the surface flattening and smoothing phenomenon occurr in laser ablation of material. Strontium titanate ceramic substrate with the thickness of 0.3 mm can be shape cut by selecting appropriate laser processing parameters.