The produce of small surface and inner cracks is inevitable in metallic structural that is subjected to complex and cyclic loading. The growth of the crack threatens the safety of structure, and may results in serious consequences. It is very important to detect the presence of cracks by non-destructive testing. In this paper, a novel technique for detection and location of small cracks is presented. The metallic structural is radiated by lasers to produce ultrasonic and the state space predictive model is constructed based on the dynamical responses in time domain. A nonlinear damage feature is then extracted from the model to indentify the crack. Furthermore, the crack is located and visualized by using the feature extracted from the entire scanned area. An example of the technique and experimental detection are given for alloys with different cracks. The experimental results show the reliability of the technique.