Crack is one of the measure catastrophic failure in mechanical machines so it’s necessary to detect it in early stage. In this paper proposed a method to identify crack in early stage. The purpose of this study is to describe relation between modal natural frequencies change due to crack in shaft with respective crack parameters like Depth, Location and Width. Analysis is done for Single Crack and is evaluated. Analysis reveals how modal natural frequency decreases with change in crack size. It has been observed that when shaft suffers from a crack or any damage then its dynamic properties changes. Crack causes a reduction in stiffness and ultimately reduction in its modal natural frequencies which leads to change in dynamic response of the shaft. The results of modal analysis using FEA are validated with experimental modal analysis.