In this study try to synoptic Analysis heavy rainfall 66.8 mm led to flood on 27 Feb. 2010 in eyvangharb region situated in west of Iran. First by data from terrestrial station heavy rainfall was recognized. Then by data from upper atmosphere and draw related maps, heavy rainfall of eyvangharb was evaluated. drawn and analysis of maps shown that intense pressure gradient between low pressure seat in west, Northwest and central of Iran with high pressure of north of Caspian sea from north, high pressure seat on west of china from east, and also high pressure from northeast of Africa from west, and west south lodgment deep of trough on Iraq, Saudi and east of Mediterranean sea on all level and Iran lodgment in east of trough and under the region of upper divergence and also upward air in the all of level that caused climb and instability. Negative values of eddy that shown existence of it for all atmosphere levels. In addition high thickness of air at heavy rainfall time and also positive vorticity values at all levels indicate divergence flow and ascending air for all levels of air is the agents for occurrence heavy rainfall. seat of polar front jet stream on west of country and merge it with jet stream seats on European and Mediterranean sea from west and jet stream seats on west china from east, caused heightened instability and produce baroclinic conditions for eyvangharb. finally main resource of humidity of rainfall in eyvangharb at(500, 600 and 700 hectopascal)are from Mediterranean sea and red sea, but at levels near the earth surface (850, 925 and 1000 hectopascal), Caspian sea plays a main role in provide of humidity in heavy rainfall. The maps showed merge and convergence of humidity on west and northwest of Iran that one of main reason for heavy rainfall occurrence.