The invention discloses a CDN service IP detection method and system. The method comprises a step of sending a domain name resolution (DNS) request to a DNS server, and extracting the IP address included in a DNS response packet returned by the DNS server, a step of sending a hypertext transfer protocol (http) request to the IP address and obtaining http response information, a step of extracting the attribute value of a CDN identification attribute according to the DNS response packet and the http response information, and a step of judging whether the IP address is a CDN service IP by using a CDN classifier formed according to the Naive Bayesian principle according to the attribute value of the CDN identification attribute and outputting a judgment result. According to the method, by using multiple CDN identification attributes, the analysis is carried out through the CDN classifier formed according to the Naive Bayesian principle, compared with traditional simple judgment only for one or more characteristics, the judgment of the invention is more accurate, and wrong judgment due to a condition that a site does not have a characteristic is avoided. In addition, the selected CDN attribute is obtained through a large number of actual website data and is more authentic and reliable.