Direct ethanol fuel cells are among the most efficient and environmentally friendly energy-conversion devices and have been widely focused. The ethanol oxidation reaction (EOR) is a multielectron process with slow kinetics. The large amount of by-product generated by incomplete oxidation greatly reduces the efficiency of energy conversion through the EOR. In this study, a novel type of trimetallene called porous PdWM (M = Nb, Mo and Ta) is synthesized by a facile method. The mass activity (15.6 A mg Pd −1 ) and C1 selectivity (55.5%) of Pd 50 W 27 Nb 23 /C trimetallene, obtained after optimizing the compositions and proportions of porous PdWM, outperform those of commercial Pt/C (1.3 A mg Pt −1 , 5.9%), Pd/C (5.0 A mg Pd −1 , 7.2%), and Pd 97 W 3 /C bimetallene (9.5 A mg Pd −1 , 14.1%). The mechanism by which Pd 50 W 27 Nb 23 /C enhances the EOR performance is evaluated by in situ Fourier transform infrared spectroscopy and density functional theory calculations. It is found that W and Nb enhance the adsorption of CH 3 CH 2 OH and oxophilic high-valence Nb accelerates the subsequent oxidation of CO and -CH x species. Moreover, Nb promotes the cleavage of C-C bonds and increases the C1 selectivity. Pd 60 W 28 Mo 12 /C and Pd 64 W 27 Ta 9 /C trimetallene synthesized by the same method also exhibit excellent EOR performance.