A squall line was recorded in Dayyer port on 19 Mar 2017. In this study, the properties associated with the squall line, as well as precipitation associated with this phenomenon, with 3DVAR and 4DVAR data assimilation and without (CTRL) data assimilation is simulated for 18UTC 18 March, 2017 in two domains with a horizontal resolution of 27 km and 9 km. In this study, Bushehr Doppler Weather Radar (DWR) observations (radial winds and reflectivity) are used. In order to verification of the properties associated with the squall line event, wind speed, sea-level pressure, temperature, relative humidity and precipitation accumulation were compared with the corresponding observation. The results showed that data assimilation in two ways enables simulation of the squall line. Also, comparing the 3DVAR and 4DVAR have showed that 4DVAR compared to 3DVAR in wind speed, sea level pressure and precipitation accumulation has improved by 12/23%, 8/98% and 35/16%, Respectively.