By means of density functional theory(DFT) and self-consistent reaction field of polarizable continuum model approach,the one-pot synthesis mechanism of cyclic alkenyl ethers via intramolecular cyclization of o-alkynylbenzaldehydes catalyzed by CuI has been investigated.The results suggest that the regioselectivity is thermodynamic favoring 6-endo-dig cyclization,and the overall reaction includes the activation of the substrate,an intramolecular cyclization step,a nucleophilic attack of the methanol on the carbonyl carbon,proton migration and the catalyst reproduction.The intramolecular cyclization is the rate-controlling step in which CuI decreases the relative Gibbs free energy of the transition state by 163.9 kJ/mol.The catalysis essential of CuI is the coordination of copper(I) to the triple bond which can remarkablely decrease the orbital energy of π_c1-c2^* and the orbital energy-gap between π_c1-c2^* and LP-(2p)O1.MeOH plays dual functions:as a nucleophile to attack on carbonyl carbon,as a proton shuttle to transport a proton from a nucleophile to the alkynyl-carbon.