Phosphorus and boron fertilizers play an important role in the tobacco oil synthesis.The change of the content of oil and its precursor (chlorophyll，organic acid，pyruvic acid) with different phosphorus and boron fertilizer had been studied in open field cultivation in order to explore the effect of phosphorus and boron fertilizer on petroleum extract.The results showed that the petroleum extract was the highest when phosphorus and boron fertilizer were applied at 112.5 kg/hm2 and 3 kg/hm2.The oil content could be higher with the increasing of phosphorus and boron fertilizer,while lower phosphorus fertilizer might limit the effect of boron fertilizer and wasnt conducive to synthetic petroleum extract.The content of chlorophyll,organic acid and pyruvic acid showed positive correlation with the oil content of the flue-crued tobacco,and the higher precursor could increase the oil content.