The invention belongs to preparation of aromatic hydrocarbons from synthetic gas, and more specifically relates to a catalyst and a method for preparing aromatic hydrocarbons by direct conversion of synthetic gas. Synthetic gas is used as a reaction raw material, a conversion reaction is carried out on a fixed bed or a moving bed, the catalyst is a composite catalyst A+B, the catalyst A and the catalyst B are compounded by a mechanical mixing mode, an active composition of the catalyst A is an active metal oxide, and the catalyst B is one or two kinds or above of ZSM-5 molecular sieve or metal modified ZSM-5; the space between a geometric centre of the active metal oxide of the catalyst A and a geometric centre of particles of the catalyst B is between 5nm and 4mm, and preferably 5nm-1mm; the weight ratio of the active composition of the catalyst A to the catalyst B is 0.1-20 times. The pressure of the synthetic gas is 0.1-6MPa, the reaction temperature is 300-600 DEG C, and air speed is 500-8000h<-1>. The reaction process has good product yield and selectivity, selectivity of aromatic hydrocarbons reaches 50-85%, selectivity of by-product methane is lower than 15%, and the product and the method have good application prospects.