The relationship between Phyllocnistis citrella and citrus canker,was investigated at Guojiaba town in Zigui County,Hubei Province from April,2017 to October,2018.The results showed that P. citrella and citrus Canker occurred at the same Position based on the field observation and symptom comparison. Citrus canker diseases spread along with paths on leaves caused by P. citrella. The disease symptoms were varied as powdery during the high-incidence period of P. citrella. The 20 years data of P. citrella quantity of 100 leaves,occurrence area of citrus canker and disease index of citrus canker from Plant Protection Station of Zigui County showed that there was inter-annual and annual synchrony of increase and decline dynamic in incidence of P. citrella and citrus canker disease . Pathogens from the paths caused by P. citrella were molecularly identified as casual pathogen of citrus canker. It is indicated that P. citrella is an important factor for spreading citrus canker disease and increasing its severity. Preventing the incidence of P. citrella will be effective for controlling citrus canker disease.