Abstract: Mei symmetry and Mei conserved quantity for Appell equation in Chetaev constraint mechanical systems are investigated.Appell equations and differential equations of motion for Chetaev constraint mechanic systems are established.The relation between Lagrange function and A function is analyzed.An general research approach of Mei symmetry and Mei conserved quantity for Appell equation in Chetaev constraint mechanical system is discussed.The definition and the criterion of Mei symmetry of Appell equations under the infinitesimal transformations of groups are given.The constructional equation of Mei symmetry and the expression of Mei conserved quantity are also obtained.An example is given to illustrate the application of the results.