An effective partially premixed flamelet model for large eddy simulation (LES) of turbulent spray combustion is formulated. Different flame regimes are identified with a flame index defined by budget terms in a 2-D multi-phase flamelet formulation, and the application in LES of partially pre-vaporized spray flames shows a favorable agreement with experiments. Simulations demonstrate that, compared to the conventional single-regime flamelets, the present partially premixed flamelet formulation shows its ability in capturing the subgrid regime transitions, yielding a well prediction of peak gas temperature and the downstream flame spreading. A propagating premixed flame front is found coupled with a trailing diffusion burning through the spray evaporation, and the spray effect on regime discrimination is manifested with transport budget analysis. A two-phase regime indicator is then proposed, by which the evaporation-dictated regime is properly described. Its intended use will rely on both gas and spray flamelet structures.