Abstract: Statistics from oil physical properties of main strata in Huanghekou depression show that physical characteristics of oil depend not only on group compositions, but also on maturity, burial depth, preservation condition and compositional gravity differentiation. The factors influence on density include content of saturated hydrocarbon, aromatic hydrocarbon, resin, asphaltene and wax. Viscosity mainly depends on content of saturated hydrocarbon, aromatic hydrocarbon and resin, not on asphltene and wax. The authors believe that the distribution rule of physical properties of oil in Huanghekou depression is the result of multi-factors combinations. Among all the factors, hydrocarbon source differences, biodegradation, migration and the reservoir preservation condition are the main influence factors resulting in discrepancy of physical properties.