Abstract: In this paper, some properties of a strong-coupling exciton in piezoelectric crystal are studied. An effective Hamiltanian of the exciton is obtained by the method of a linear-combination operator and a simple unitary transformation. The self-energy could be written as a series in α^-1, the first term being proportional to α, the coupling constant. The interaction potential induced by the interaction of the electron-hole with the phonons is related to coupling constant and sound speed etc.