NOVELTY - Proton exchange membrane fuel cell electrocatalyst comprises a hollow spherical two platinum-based alloy catalyst which is supported on a carbon carrier, where the wall of the hollow sphere is set with a through hole. The binary platinum based alloy nano-particles (PtxMy) has atomic ratio (x and y) distribution of 10:1-1:1. The content of platinum-based alloy catalyst supported is 10-40 wt.%. The second metal (M) is lead, iron, nickel or copper.    USE - Used as proton exchange membrane fuel cell electrocatalyst.    ADVANTAGE - The electrocatalyst has good controllability. The method is simple, and is economical, and thus it easily achieves large-scale industrial production; has mild preparation conditions; and saves energy.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing electrocatalyst, comprising (i) protecting the to be protected catalyst, coordinating by adding a complexing agent, etching the hollow core and binary metal wall of the porous structure of nanoparticles by adding an etching agent, then uniformly purifying the carbon support surface, and carrying out pro-settlement process for preparing support, and obtaining porous wall hollow core platinum-based alloy catalyst, where the complexing agent used is bromine based- reagents including potassium bromide, sodium bromide or cetyltrimethylammonium bromide (CTAC), and the etching agent used is chlorine based reagents including potassium chloride, sodium chloride or CTAC; and (ii) preparing coordination compounds using protective agent contacting with a second metal forming agent or protecting the salt micelles formed with the transition metal, or taking a steric hindrance agent, where the coordination compounds can be formed with a second metal comprises trisodium citrate or sodium o-phenyl ethylene diamine, and the transition metal salt capable of forming a protective micelle include cetyl trimethyl ammonium chloride, cetyl trimethyl ammonium bromide or sodium dodecyl benzene sulfonate, and the steric hindrance agent is polyvinylpyrrolidone.