Abstract: Recent researches of solid acid catalyst in the upgrading process for biomass pyrolysis oil (bio-oil) were reviewed. The advantages and shortcomings of several important solid acid catalyst，such as molecular sieve and SO42－/MxOy were analyzed and compared. It was pointed out that the currently used methods in upgrading bio-oil were catalytic pyrolysis and esterification. According to the properties of bio-oil，converting carboxyl acid and aldehyde through esterification and aldolization have great potential.