The screening for Black rot(Xanthomonas campestris PV.campestris)resistance in broccoli (Brassica oleracea L.Var.italica Planch) lines plays an important role in breeding for Black rot resistance and is of great value to practical utilization.The broccoli in bred line91-9318-4was used as the experimental material in the trial.X0-2 strain of Xanthomonas campestris PV.campestris was and purified from the infected broccoli plants in the field.The spraying method was adopted in the inoculation.The trial was designed as the randomized blocks of two factors with three replications.Factor A was the foliar age and factor B was the concetrations of inoculum.Factor A had three levels A1,A2 and A3 (the 2nd 4th and 6th true-leaf stage),factor B had three levels B1,B2 and B3(106 counts/mL,107 counts/mL and 108 counts/mL).26 breeding materials of broccoli were identified for resistance to Black rot by means of the acquired method.One resistant breeding material was obtained,the identifying results showed that this screening method is practical.