The invention provides a safe and rapid public WiFi (Wireless Fidelity) authentication method. When a mobile terminal accesses any webpage, a Portal gateway is redirected to a Portal server and the webpage is returned back to a mobile terminal; the webpage comprises a URL (Uniform Resource Locator) linkage and the URL linkage carries information parameters; the mobile terminal analyzes the information parameters to obtain formation fields; the formation fields, self information of the mobile terminal and a key provided by a WiFI Portal service provider are combined and then are subjected to MD5 encryption to obtain a first character code; the first character code is packaged again to obtain a URL request linkage and a request for surfing the Internet is asked from the Portal server; the request linkage comprises the first character code and information for generating the first character code; the Portal server obtains a second character code according to the same encryption manner; the first character code is compared with the second character code; if the first character code and the second character code are matched successfully, the Internet surfing is allowed; otherwise, the Internet surfing is prohibited. The invention further provides a safe and rapid public WiFi authentication system; the safety of public WiFi is improved and complicated operation of networking of a user is simplified; and the user experience is improved.