To study the mechanism of tobacco nicotine conversion,the expression of nicotine conversion related proteins of high tobacco nicotine conversion was explored by differential proteomics. Two dimensional electrophoresis combining MS spectrometry were used to compare the expression of the proteins between high nicotine conversion tobacco (experimental group) and wild type tobacco (control group). After obtaining the distinguishable and repeatable 2 D pictures,there were 34 different proteins spots between the two tobacco plant leaves.12 different protein spots were then identified by the Matrix Assisted Laser Desorption/ Ionization time of Flight Mass Spectrometry Mass Spectrometry (MALDI TOF TOF MS),including 7 protein spots down regulated in white flower leaves (experimental group),and 5 protein spots up regulated. In addition to comparison analyses with proteomic database,these proteins are involved in carbohydrate,energy metabolism and so on. Most of them are chloroplasts or mitochondria proteins. In a whole,these differential expression proteins were closely related with tobacco nicotine conversion,which can provide another pathway for finding the mechanism of tobacco nicotine conversion.