Web Phishing has become a big threat to online applications such as financial services,it steals user identities and credentials by imitating the sites of service providers such as banks.This paper proposes a novel architecture of Phishing Web detection which gives the function modules and processing workflow,and a visual based Web page similarity detecting algorithm.Based on the image of the suspicious Web page,the algorithm first divides Web page into sub-block images from which features and relations are Abstracted and the ARG(Attributed Relational Graph)of the Web page is formed.Then based on the ARG of two Web pages,we get the Nested-EMD(Earth Mover's Distance)of the two pages as their similarity,and then the decision can be concluded by comparing the similarity degree between two Web pages.The algorithm is implemented and compared with the latest international researches,and it is shown that the algorithm is better in accuracy and robustness according to the experiment.