By statistical analysis of petrophysical properties of outcrop and core samples and spectral structure of 1∶500,000 integrated reduced gravity data, 6 tectonic layers of Qiangtang Basin were identified and separated by matched filter. Gravity inversion algorithm coupled with topography was employed to caclculat the top/bottom structures and the thickness of the Jurassic tectonic layer. 5 depressions in the Northen Qiangtang sag and 4 depressions in the Southen Qiangtang sag were predicated. These 9 depressions are distributed along with the periphery of central uplift belt, the sediments in the 5 depressions in Northern Qiangtang are attributed to evaporates of transitional facies with total sedimentary volume slightly less than that in Southern Qiangtang. In combination with Jurassic outcrop lithology and stratigraphy, lake and spring water geochemical data and remote sensing image interpretation the depressions in Northern Qiangtang were estimated to have more favourable conditions for halite sylvite sedimentation than those in Southern Qiangtang. Two depressions (QB2 and QB3) in Northern Qiangtang were preliminarily evaluated as the first rank prospective ones for evaporate sedimentation and two depressions (QN1 and QN2) in Southern Qiangtang as the second rank ones.