Analytical Modelling is the initial step in a software based Finite Element Analysis of any sophisticated structure associated with irregular shape, complex loading pattern and combination of different loads along with complex boundary condition. In the modelling of structure, Mesh Density plays a major role and it becomes a critical issue of finite element analysis, which closely relates to the accuracy of finite element model while directly determine their complexity level. This project report presents a systematic study on finding the effects of Mesh density on accuracy of numerical analysis results, based on which brief guidelines of choosing the best mesh strategy in finite element modelling is provided. In the project work, for studying the effect of Mesh Density, a bridge deck has been considered and analysis has been performed separately for Self-weight of the structure as well as Vehicular loading which is dynamic in nature. The modelling of the Bridge deck is performed several times with different mesh sizes for studying the analysis results to accomplish the best Mesh strategy that maintain the complexity level of the modelling without compromising in the accuracy of the analysis results. In addition, a case study on similar kinds of attempts to establish perfect Mesh size has been discussed briefly and a comparison has been made between the conclusions of this project work with the case study results, which are in line up to a great extent.