This study is a part of research for developing the technologies of long life pavements having more than 40-year design life. The objective of this study is to develop the simplified design procedure for determining the layer thickness and modulus of the long life pavement. A synthetic database was established using the finite element program of a pavement structure with various combinations of layer thickness and modulus. The synthetic database includes the structural and material information, surface deflection, and critical pavement responses. Using the developed synthetic database, this paper suggests the minimum layer thickness and modulus for long life pavements bared on the limited strain level concept. Results demonstrate that the pavement greater than 410mm of total AC layer thickness is considered as the long life pavements regardless of the material characteristics and thickness in each layer. To become a long life pavement, a total thickness of AC layer should be greater than 250mm. The design procedure for determining the layer thickness and modulus of the pavements with AC layer thickness ranging from 250 to 410mm is also presented in this paper.