Abstract: The purpose of this project was to establish a fast, reliable and easy method to determine the virulence of walnut canker. Mycelium, spore suspension and bacterial suspension were inoculated on 1, 2 and 3 years old branches of ‘Wen 185’ with different wound treatments, and then pathogenic severity was observed with 4 different temperature treatments and then the optimium disease condition was obtained. The results showed that the canker of 3 years old walnut was most serious and the lesions length was up to 8.5 cm; the most ideal inoculum and wound treatments were agar disk and scalding because the lesions length was up to 9.8 cm; 25℃ was the optimum temperature for pathogenic bacteria to grow and the lesions length was up to 11 cm, and there was no difference of the inoculation time after scalding for the growth of pathogenic bacteria. The research results provide theoretical basis for a rapid laboratory determining method of walnut canker pathogenicity.