On the basis of ascertaining that phosphomolybdic acid modified platinum electrode has higher catalytic activity to methanol oxidation, three kinds of transition metal substituted phosphomolybdic acids were synthesized, and the IR spectrum indicated that the compounds still kept Keggin structure. The transition metal substituted phosphomolybdic acid modified platinum electrodes were prepared, and the electrochemical behaviors of the transition metal substituted phosphomolybdic acid modified platinum electrodes and their electrocatalytic effects to methanol oxidation were studied. Meanwhile, the results showed that the three kinds of heteropolyacid modified platinum electrodes had higher electrocatalytic activity to methanol oxidation, manganese substituted phosphomolybdic acid modified platinum electrode had the highest electrocatalytic activity among them.