Website access performance monitoring method, device and system

The embodiment of the invention provides a website access performance monitoring method, device and system. The device comprises a DNS (Domain Name System) probe request unit, DNS data acquisition unit, an HTTP (Hyper Text Transport Protocol) probe request unit, an HTTP data acquisition unit, a DNS available rate calculation unit, a HTTP available rate calculation unit, an access performance calculation unit, a warning information generation unit and a warning information output unit, wherein the DNS probe request unit sends a DNS probe data request to a DNS server; the DNS data acquisition unit obtains DNS probe data containing CNAME (Canonical NAME) data and NS data fed back from the DNS server; the HTTP probe request unit sends the HTTP probe data request to a Web server; the HTTP data acquisition unit obtains the HTTP probe data fed back from the Web server; the DNS available rate calculation unit generates DNS service state data and DNS service available rate data; the HTTP available rate calculation uni