The formation and growth of voids is of intense interest for material performance at elevated temperature, because they can have a profound influence on material properties. In this presentation, a void nucleation and growth model is established based on the vacancy and interstitial concentrations from a newly developed continuum dislocation dynamics model with point defect generation mechanism. The model is capable of simulating void evolution due to dislocation activities during cyclic plastic deformation. A Monte Carlo approach is developed as the criterion for void nucleation. The critical size of void embryo is obtained based on the free energy from vacancy and interstitial fields. Then the void nucleation rate is calculated for a given local conditions (temperature, stress, and point defect concentrations). The growth of void is obtained by calculating the flux of vacancy and interstitial into the void after it formed. It is done by solving the diffusion equations of vacancy and interstitials. A test simulation is performed in which void nucleation and growth are observed from the evolution of total void volume and void nucleates randomly both in space and time. The void nucleation and growth model is then applied to the crack simulation with dislocation dynamics. It was observed that the void nucleated in a region with high vacancy supersaturation ratio near the crack tip as observed in experiments.