In this research,shipborne samples were randomly selected from imported Canadian rapeseeds to investigate the occurrence of phoma stem canker(Leptosphaeria maculans) by PCR amplification,pathogen isolation and pathogenicity test. The results showed that all fifteen rapeseed samples from three ships were positive in PCR detection of Leptosphaeria maculans.The results from pathogen isolation, identification and pathogenicity testing of three randomly selected samples confirmed the PCR detection.