The title compound [C4H12N2]3[PMo12O40] was synthesized from the hydrothermal reaction and charac- terized by IR, elemental analysis and X-ray signal crystal structural analysis. The crystal of the title complex belongs to trigonal space group R3c with a=1.788 62 nm, c=2.354 3 nm, and V=6.522 62 nm3, Z=6, R1=0.038 4, wR2 =0.102 0. The compound consisted of piperazine and PMo12O403 - , and the structure is extended to three dimensional framework owing to the hydrogen bond between the O atoms and N atoms. The bulk-modified carbon paste electrode (APM-CPE) using this compound as modifier shows a good electrocatalytic activity toward the oxidation of ascorbic acid(AA).