Abstract: Gravity field in Qiangtang basin is of correlation in different levels with landform, which is the most principal feature. Among them the Level-Ⅱ is the most important correlation. Study shows that crustal low resistivity zone should be the crustal isostatic adjustment surface; upward highland is corresponding to downwarped low resistivity zone block, both shape isostatic cylindrical body (ICB) of mountain massif. In contrast, downparped lowland is corresponding to upward low resistivity zone, constituting reverse ICB of mountain massif. Hence, ICB appears to be multi-side shapes with an area of about 1x10⁴km². In north Qiangtang area, the ICB occurs in array of inverse “V” form; while the reverse ICB arranges in E-W orientation. They imply the petroleum geologic significance that south and north Qiangtang should be basins of different features; the large gravity lows are not deep depression deposits but reconstructed isostatic upward and rising structural zones; the low resistivity zone uplifting might change the basin into relatively cold or hot crust and cold or hot basin, thus having more impor-tant efcts on its thermal evolution of hydrocarbons.

Key words: Qiangtang basin, gravity field, landform, structure, uplift, depression