Abstract: A review regarding the investigation of the background circulation of large scale low-level jet over East Asia is given, which indicates the important effect of the monsoon westerlies on LLJ and the relationship between LLJ and cross-equatorial currents.The data of the Global Analyses provided by ECMWF are used to investigate the relationship between LLJ and monsoon as well as cross-equatorial currents. It indicates that a large amount of momentum of the monsoon westerlies is transferred downstream to the low-level jet area, strengthening the jet speed. Most of the LLJ over Asia are connected with the cross-equatorial currents in Eastern Hemisphere. The cross-equatorial currents near 80°E are the main currents connected with LLJ in May. However, once the Somaria jet is. established, it becomes the main flow together with the cross-equatorial currents. near 105°E to influence the low-level jet over East Asia.