Method and device for detecting junk mail

The invention provides a method and device for detecting a junk mail. The method includes: generating a sample vector according to a sample library and a feature word lexicon which includes normal mail type feature words and junk mail type feature words which are extracted from sample mails of the sample library; selecting a linear kernel function of a support vector machine, using the sample vector as input and training to obtain a classification function; determining weights of feature words in the feature word lexicon according to a coefficient of the classification function, picking up feature words whose weights are nonzero values to generate a feature word set, and determining a judging threshold value according to an offset of the classification function; and making statistics of a sum of the weights of the feature words contained in a mail to be detected according to the feature word set, and judging the mail to be a junk mail when the sum of the weights exceeds the judging threshold value. The method for detecting a junk mail saves the calculation amount of a detection process, and improves detection efficiency under the condition of guaranteeing detection precision.