An effective gear design balances strength, durability, reliability, size, weight and cost. Because of the advantage of gear, gearbox was used widely. But its fault also brought many losses of the production and society. It was necessary to research and analysis on the dynamical behavior of the gear system. The engineering structures may fail due to crack, which depends on the design and also on operating conditions in which it operates. It can be avoided by analyzing and understanding the manner in which it originates. It is necessary to develop design guidelines to prevent failure modes considering gear tooth fracture, by studying the crack propagation path in a gear. In variety of gear tooth geometry the crack propagation paths are predicted at various crack initiation location. The objective of this study was to follow the crack propagation in the tooth foot of a gear by the Finite Element Method (FEM). The study concludes with the analysis of available for standard gears, to highlight the different behavior in crack propagation. The influence of crack position and crack depth etc. on dynamic characteristics of gear has also been studied.