Introduction: According to structural changes in western Alborz range from south to north, field geology and tectonosedimentary studies carried on western Alborz, We divide western Alborz range to several tectonostratigraphic zones.Aim: Alborz mountain range is very complicated and interpretation and recognition of geodynamic evolution of Alborz is needed to recognition of geological zones.Materials and Methods: study of deformation styles, faults and their effects on sedimentation, unconformities, Lithological variations in the same periods of geological times, specially from Jurassic period, indicate different geological conditions and are used as fundamental factors for tectonosedimentary zonations of western Alborz mountain range.Results: Alborz Magmatic assemblage (3) is a volcanic arc erupted due to subduction of an oceanic plate under a continental crust (3). Southern and Central Alborz comprise of several rock units of Paleozoic and Mesozoic Era which unconformably underlain by Eocene volcanic rocks. These zones are affected by Early Cimmeride, Late Cimmeride, Austrian, Laramide Pirnean, Attican and Pasadenian orogenic phases. The effects of Late Cimmerian and Austrian orogenic movements in the Median and Southern Alborz are visible in the form of unconformities, but in Northern Alborz which is situated in the northern side of Deylaman and Dorfak faults, there is no evidence of unconformity in rock units of lower Cretaceous time. According to geological investigations, a subsidence phase began in Upper Jurassic and continued to Upper Cretaceous in Northern Alborz zone accompanied by volcanic activity. Northern Alborz comprises of Paleozoic and Mesozoic rocks and the folding rate in this area is less than Central and Southern Alborz zones. After Jurassic period, some variations occur in the rock units of Central and Southern Alborz because of different geologic conditions prevailing in these tectonosedimentary zones. Khazar Coastal Plain or Gorgan- Rasht zone consists of a metamorphic basement and is overlain by thick Quaternary sediments.Conclusion: A correlation between rock units, structural forms, petrotectonic data led to the divisions of Western Alborz Mountain into five tectonosedimentary zones named as: South Alborz Magmatic Assemblage,(3) Southern Alborz, Median Alborz (with Manjil- Shahroud valley and Rostam Abad- Asiabar- Alamkuh subzones), Northern Alborz and Gorgan- Rasht Plain. These zones are separated from each other by several large, deep seated faults.