Catalytic hydrogenation of acetic acid to ethanol was investigated in a fixed-bed micro-reactor with calcium silicate-modified platinum-tin catalyst at mild reaction condition. The modified catalyst exhibited excellent performance for the ethanol synthesis process at relatively low pressure. According to the results of H-2-pulse chemisorption experiments, the introduction of calcium silicate promoted the dispersion of platinum particles. The NH3-TPD and H-2-TPR results showed the decrease of acid content on catalyst surface and the enhancement of reducibility after the CaSiO3 modification. Additionally, the results of XPS indicated that Sn (0) was emergent and Pt (2+) was sharply decreased after reduction. Both the H-2-TPR and XPS results supported the formation of Pt-Sn alloy during the reduction process at 623K. The Pt-Sn alloy changed the electron density and benefited the free hydrogen dissociation and hydrogenation. The enhancement of reaction temperature and pressure both promoted acetic acid conversion. The kinetic model of power-function type was established to describe the process of hydrogenation. The results of residual analysis confirmed that the raised kinetic model for acetic acid to ethanol reaction was suitable.