Abstract: The study of damage pattern growth in brittle materials is of fundamental importance for understanding the gestation mechanism and the occurrence conditions of catastrophe in some key project constructions. It is especially important in understanding the dynamic catastrophe in rock, such as seismic, rock burst, and the three kinds of outburst which are the outburst of water, gas and coal in coal underground mining. A great many studies showed that the mechanism of formation of the dynamics catastrophe in rock can be explained in the same mode that irreversible evolution of damage in material induces catastrophe in structure. So the study of the growth of damage pattern is a great important method to understand the course of gestation and occurrence of the catastrophe, and the simulation of growth of damage pattern is a good way to demonstrate the course of gestation and occurrence of the catastrophe. In the paper, damage pattern growth in a 2-D sample of quasi-brittle material is simulated, which is based on the principle that the damage evolution is irreversible, and the lattice finite element is used for the numeric model. The simulation displayed that the damage pattern in the 2-D sample grows in a way of irreversible expandedness from a point to large scale cracks, which are fractals formed of lines and planes. The damage mechanism is based on the strength theory of tension strain for brittle materials, and the computer program is developed on the platform of ANSYS. The conclusion showed that the complex shape of a damage pattern can be deduced from the simple dynamic rule of the meso-element and the interaction between the meso-elements, and the boundary of the pattern moves forth in fractal shape. In the end of the paper, some inspirations for catastrophe prediction are discussed.