The composite materials consist of two or more different materials that form regions large enough to be regarded as continua and which are usually firmly bonded together at the interface. Many natural and Synthetic materials are of this nature, such as: reinforced rubber, filled polymers, GFRP (Glass Fiber Reinforcement Plastic), Nylon, aligned and chopped fiber composites, polycrystalline aggregates (metals), etc. It is widely used in high speed machinery, aircraft and light weight structures. Crack is a main cause of damage occurring upon dynamic loading and may cause serious failure of structure. The influence of cracks on dynamic characteristics like natural frequencies, modes of vibration of structures has been investigated. The paper presents the Computational modal analysis of a composite beam with and without cracks. In this work, the mechanical properties of aluminum and fiber (Nylon and Glass fiber reinforcement plastic) are measured a universal testing machine. The three-dimensional finite element models of composite beam with and without cracks are constructed and then computational modal analysis on ANSYS-14 is then performed to generate natural frequencies and mode shapes. The location of cracks will vary from 10 to 90 % of beam length. The finite element model agrees well with the analytical values.