The Mechanistic-Empirical Design provides more insight into pavement behaviour and performance than the 1993 AASHTO empirical method. The new Mechanistic-Empirical Pavement Design Guide (MEPDG) developed under the National Corporation Highway Research Program (NCHRP) 1-37A. A hierarchical approach is employed upon traffic, climate and materials input to produce pavement performance predictions of smoothness and numver of distress types. One of the most significant changes offered in the Mechanistic Empirical Design Guide (ME PDG) is the difference in the method used to account for highway traffic loading. Traffic volume and traffic loads, the two most important aspects required to characterize traffic for pavement design are treated separately and independently and its use-oriented computational software implements an integrated analysis approach for predicting pavement condiditon over time that accounts for the interaction of traffic, climate and pavement structures. The recently developed guide for mechanistic-empirical (M-E) design of new and rehabilitated pavement structures will change the way in which pavements are designed by replacing the traditional emprirical design approach in the AASHTO 1983 Guide. The M-E Pavement Design Guide will allow pavement designers to make better-informaed decisisions and take cost-effect advantage of new materials and features. However, the proposed design guide is substantially more complex than the 1983 AASHTO design guide. It requires more imput values from the designer. There is limited availability of the data for many MEPDG inputs.This project report presents the Mechanistic-Empirical approach of Pavement Design for New and Rehabilitated Flexible Pavements using the new ME PDG. The main objectives of the report are: (1)to demonstrated how the Mechanistic-Empirical design of pavement is more precise than the existing empirical method, (2)to explain the software input and output parameters, (3)to present a complete overview of the M-E design process and to gain a thorough understanding of the materials, traffic, climate and pavement design inputs required for M-E design.