Abstract: This review introduces the recent progresses made in the study of direct reaction and hydrocarbon-pool mechanisms for the C-C bond formation in the conversion of methanol over acid molecular sieves. It also involves in the main theoretical and experimental methods. The dehydration mechanism of methanol and the problems of direct reaction and hydrocarbon-pool mechanisms are also analysed. In addition, the effect of molecular sieve pore structures on the hydrocarbon-pool species and their reaction mechanism was evaluated.