The alkylation of isobutane with mixed C4 olefins catalyzed by sulfuric acid was investigated under conditions of industrial interest. On the basis of previous work, the alkylation kinetic model was improved, in which the fast isomerization between butenes was fully considered and the formation pathways of the heavy ends (HEs) were modified. Satisfactory agreement between experiments and model calculations was achieved with the concentration profiles of three key components in alkylate, i.e. trimethylpentanes (TMPs), dimethylhexanes (DMHs), and heavy ends (HEs). The reliability of the kinetic model was further verified by predicting the isobutane alkylation by mixed C4 olefins with different compositions. In addition, density functional theory (DFT) calculations were performed to confirm the fast isomerization between butenes. MD simulations reveal that butenes can diffuse more easily than isobutane in the H2SO4, facilitating the fast polymerization reaction and the growth of heavy ends (HEs). It is hopeful that the kinetic model developed in this work will provide a fundamental reference for the design and optimization of the industrial alkylation process.