The　alkylation　of　3-methylthiophene(3MT)　with　isobutene(IB)　was　selected　as　a　model　reaction.　The　number　of　independent　reactions　was　determined　by　chemical　stoichiometric　matrix.　All　basic　property　data　of　alkylated　products　was　estimated　by　the　group　contribution　method.　The　heat　of　reaction　and　Gibbs　free　energy　for　each　independent　reaction　at　different　temperatures　were　calculated　by　UNIQUAC　equation.　The　effects　of　temperature,　pressure　and　feed　composition　on　conversion　of　3MT,　formation　amount　of　IB　dimer　and　distribution　of　alkylation　products　were　analyzed　by　Aspen　Plus　software　simulation.　The　thermodynamics　analysis　results　revealed　that　conversion　of　3MT　can　reach　a　high　level　at　the　certain　range　of　temperature,　pressure　and　feed　composition.　Under　conditions　of　initial　mass　fraction　of　3MT　1.0%(based　on　feed　total　mass),　2　MPa,　and　273-453　K,　conversion　of　3MT　was　above　99%.　High　temperature,　low　pressure　and　high　3MT　concentration　can　inhibit　IB　dipolymerization.