Abstract: In order to clarify the differentiation of physiologic races of Pseudomonas syringae pv. tabaci. in Heilongjiang,28 tobacco cv. were pin-prick inoculated with the 15 isolates of Pseudomonas syringae pv. tabaci collected from main tobacco growing areas in Heilongjiang. A set of differential hosts for identifying the physiologic races was established by determining the resistance of the tested varieties with the differential analysis and cluster analysis of disease incidence,and the 15 isolates were divided into 4 physiologic races referred to as Ⅰ,Ⅱ,Ⅲ,Ⅳ.