A dynamic box model was applied to study the characteristics of biogeochemical cycling of PO_4-P,NO_3-N,AOU,POC and PON in the southern Taiwan Strait region based on field data of the“Minnan Taiwan Bank Fishing Ground Upwelling Ecosystem Study” during the period of Dec.1987-Nov.1988.According to the unique hydrological and topographical features of the region,six boxesand three layers were considered in the model.The variation rates and fluxes of elements induced by hor-izontal current,upwelling,by diffusion,sinking of particles and biogeochemical processes were estimatedrespectively.Results further confirmed that upwellings had important effects in this region.Thenearshore upwelling areas had net input fluxes of nutrients brought by upwelling water,also had high de-pletion rates of nutrients and production rates of particulate organic matter and dissolved oxygen.Theabnormal net production of nutrients in the middle layer(10-30m) indicated the important role of bacte-ria in this high production region.Th A dynamic box model was applied to study the characteristics of biogeochemical cycling of PO_4-P, NO_3-N, AOU, POC and PON in the southern Taiwan Strait region based on field data of the “Minnan Taiwan Bank Fishing Ground Upwelling Ecosystem Study ”during the period of Dec. 1987-Nov. 1988. According to the unique hydrological and topographical features of the region, six boxes and three layers were considered in the model. The variation rates and fluxes of elements induced by hor-izontal current, upwelling , by diffusion, sinking of particles and biogeochemical processes were estimatedlypectively. Results further confirmed that upwellings had important effects in this region. Thenearshore upwelling areas had net input fluxes of agriculture brought upwelling water, also had high de-pletion rates of nutrients and production rates of particulate organic matter and dissolved oxygen. The normal net production of nutrients in the middle layer (10-30m) indicates the important role of bacte-ria in this high production region.Th