A　mesoscale　model　based　on　the　lattice　gas　cellular　automata　(LGCA)　is　proposed　for　heterogeneous　reaction　in　porous　media.　This　model　features　an　entirely　discretized　reaction　system,　including　discrete　space,　time,　gas　phases,　and　solid　particle.　To　describe　gas　diffusion　at　solid　nodes　and　gas-solid　heterogeneous　reaction　on　the　phase　boundary,　two　local　probabilities　are　proposed,　which　are　verified　by　the　analytical　solutions　for　gas　diffusion　and　gas-solid　reaction　problems.　This　model　was　then　applied　to　the　hydrogen　reduction　of　porous　Fe3O4.　The　effects　of　the　porosity,　reaction　rate　constant　(kl),　and　initial　H2　concentration　on　the　reduction　were　analyzed.　The　results　indicate　that　the　reaction　rate　increased　with　increasing　porosity,　kl,　and　H2　concentration.　The　solid　product　Fe　was　randomly　distributed　on　the　framework　of　Fe3O4　at　smaller　kl　and　concentrated　around　the　unreacted　Fe3O4　at　higher　kl,　which　is　consistent　with　our　experimental　results.