: As the most important part of road infrastructures, asphalt pavement is composed of multi-layers produced from various materials. These layers experience non-uniform loading under different thermal conditions which cause to reduction in performance and durability of pavement structure through non-uniform deformation, fatigue, and etc. Permanent deformations have detrimental effects on the asphalt pavement especially in arid areas. Thus, improvement of the asphalt layers by Geosynthetics materials as a modern method can be used to reduce destructive impacts of permanent deformations. In addition, the mechanical properties of asphalt concrete mixtures, such as creep, relaxation and recovery, have a profound impact on the design of asphalt concrete mixtures, control of pavement damages, and pavement life. So, mechanical models of asphalt concrete mixture are essential to analyze the variation of mechanical responses against the period, frequency, and amount of loading. In this study, the effects of geogrid on the viscoelastic equations of asphalt concrete mixtures have been investigated. For this purpose, mechanical behavior of concrete asphalt mixtures was investigated through urgers model. Then, the deflection in the center of loading was measured. After that, 3 samples of polyester geogrid (PET) with similar mesh size (2.5*2.5 mm ) were used. These geogrid samples, with 55, 80, 110 kN/m tensile strengths, were placed under tensile force to determine modules of elasticity and mechanical viscoelastic behavioral model through successive residuals method. For analyzing the combined model of asphalt concrete, the mechanical behavior of geogrid was considered as an elastic material. Then, the influence of it on the viscoelastic equation of asphalt concrete ( Burgers model) was firstly investigated through 3 different state: 1- the effect of geogrid on the retarded elastic strains, 2- the effect of geogrid on viscous strains (the damper of Maxwell model), 3- the Simultaneous effects of geogirds on the retarded elastic and viscos strains. On the second stage, three previous states were repeated for geogrid as a viscoelastic material. For solving the creep compliance equation (D(t)), Elastic-viscoelastic Correspondence Principle and Laplace transforms were used. Finally, the equations were solved by Matlab software. It should be noted that all investigations were studied for a layer of binder asphalt concrete (0-25) in which viscoelastic parameters were considered based on literature. To calculate deflection and creep compliance at the center of loading, static load, loading radius, and Poisson's ratio were assumed 2.8 MPa, 152mm, and 0.5 respectively based on Trucks with two axels 234 code. In the following, asphalt concrete reinforced by geogrid was modeled at Abaqus (Finite element method software) as a bulk element which include a layer of asphalt concrete and a mesh of geogrid. The results show that geogrids affect the mid-term deformations (retarded elastic strains) and permanent deformations, so the deflection and rutting amount were reduced. The most important factor of reinforcements is the strength against shear strains. So while the long-term deflection amount reduce, the long-life of pavement could be increased. Moreover, the analytical results have an excellent agreement with Abaqus results; so that, the maximum error in the output results of the asphalt concrete deflection was approximately 5%.. Keywords: Asphalt Concrete Mixtures, Geogrid, Viscoelastic, Creep Compliance, Deflection, Successive Residuals Method.