Based on the thermodynamic stability and hydrogen bond mechanisms, alkyldibenzothiophene molecular ratios, 4-/1-MDBT, 2,4-/1,4- and 4,6-/1,4-DMDBT, are used to characterize organic maturity and oil migration, which can act as molecular tracers for the filling orientation and pathway in oil reservoir. The application of aforesaid molecular parameters, in a Neogene sandstone reservoir of the XJ24-3 Oilfield, Zhujiangkou Basin and in an Ordovician carbonate reservoir of Karst pore-fissure-network type in the Tahe Oilfield, Tarim Basin, manifests that those ratios are reliable tracers compared with other molecular ratios, and thus, alkyldibezothiophene parameters may be used in a wide range of maturity, especially for high- to post-mature oil and severely biodegraded oil, both of which are short of effective molecular parameters.