The solid PW heteropoly acid catalysts supported on SiO2 are employed successfully in the alkylation of isobutane with butene under the state of supercritical fluid. Under supercritical reaction conditions, the solid acid catalysts can maintain 100% conversion of C=4 olefin during the 1400 h aging test of catalysts in the alkylation of isobutane with butene. The quick deactivation of solid acid catalysts due to coking in the alkylation can be effectively restrained and controlled under supercritical reactio...