Objective: to establish a quick molecular detection method in Beijing, which can prevent the occurrence of cucumber target spot disease from the source. Methods and results: The DNA band of Corynespora cassiicola had been obtained by PCR and sequenced. Using DNAman software and NCBI database to analyze the sequence, the results showed that the obtained DNA was that of Corynespora cassiicola on Cucumber. A specific primers CCC1/CCC2 were obtained by DNAman software and NCBI database. It was also proved to can be used to distinguish Corynespora cassiicola from other pathogenic fungi using DNAman software and NCBI database.