Abstract: A survey on tuna fishing ground has been carried out on board of 3 longliners owned by China National Fisheries Cooperation, in the high seas of the Central Atlantic Ocean from July 4th to October 27th, 2001. The relationship models between the catch rate of the different water layer ( 60m interval between 2 water layers), nominal catch rate and the environmental factors , i.e temperature, salinity and relative current velocity, were developed based on the field measured data, i.e environmental factors of the fishing ground ,fishing parameter and fisheries statistical data. They were developed by applying the habitat suitability index (HSI) model and combining the quantile regression considering the different weight of the different environmental factors and the interaction among them . Habitat environment integration index (HEII ) of bigeye tuna were estimated by these models. HEII maps of bigeye tuna were also built using the GIS software Marine Explore 4.0. The results suggest (1) From 180m to 240m, was relatively lower (<0.6) except the central area (>0.6); (2) From 240 to 300m, was relatively higher (>0.6) in the south of the 6ºN , otherwise, relatively lower in the north of the 6ºN ; (3) From 300 to 360m, was relatively lower (<0.3) except the south area (around 4ºS，23ºW); (4) In the south of the 7º N, was higher (>0.6) in dominate except a part of area (around 5ºN，22ºW; 2ºS，17ºW and 2ºS，23ºW,<0.5). Key words: Thunnus obesus; habitat environment integration index (HEII); quantile regression; the high seas of the Central Atlantic Ocean