Synthesis of n-butyl isobutyrate from isobutyric acid and n-butyl alcohol with NKC-9 cation exchange resin as catalyst was studied. The effects of reaction conditions,such as mole ratio of n-butyl alcohol to isobutyric acid,NKC-9 catalyst dosage and reaction time were examined. The kinetic data of this system were measured in a batch reactor.The optimum reaction conditions were found as:mole ratio,n(n-butyl alcohol):n(isobutyric acid)=1.4:1;NKC-9 cation exchange resin as catalyst dosage,4.0%(mass of catalyst relative to total mass of isobutyric acid and n-butyl alcohol);reaction temperature,≤125℃;reaction time,2.0 h.Conversion of isobutyric acid by the process achieves 97.6%,and activity of catalyst Can be maintained at 96.4％ conversion after being used 5 times.At the same time, the apparent kinetic modle of esterification was established,and the equation of reaction rate was derivated .