As a global 3D atmospheric chemical transport model (CTM), geoschem mainly aims at the source and sink of atmospheric components and the physical and chemical effects in the transport process, so as to simulate the actual concentration distribution and evolution process of each component. GEOS Chem uses the meteorological plants from GEOS assimilation provided by NASA's global modeling and data assimilation Office (gmao) as the initial field to drive the model. The geoschem model includes a detailed tropospheric ozone NOx VOC aerosol Hox chemical process. It fully considers the joint effect of emission sources and natural sources. It considers that the emission of CO, NOx and SO2 is taken as the default in geoschem, using Edgar 3.2's monthly global inventory in 2000, while the anthropogenic non methane VOC is used as the default, using retro 2000 as the default Geoschem uses the advection algorithm of tpcore to simulate the horizontal transport process, which is consistent with the GEOS GCM meteorological simulation, while the convective mass flux calculation includes wet deposition, dry deposition and sea salt deposition. The geoschem mixing in the boundary layer uses a non local scheme, and the simulation of mercury is extended from the original geoschem air sea coupling simulation to a coupled atmosphere ocean land model.