Abstract: The response of elastic stress and electric displacement in a long piezoelectric cylinder with a concentric penny-shaped crack is investigated in this paper. The long piezoelectric cylinder is subjected to two types of boundary conditions: ① the piezoelectric cylinder is inserted in a smooth rigid bore of radius b, ② the surface of the piezoelectric cylinder is stress and electric charge free. Based on the potential function approach and Hankel transform, a system of dual integral equation is obtained, and then reduced to a Fredholm integral equation of the second kind. Numerical results of various field intensity factors for cylinder are obtained to show the effect of the ratio a/b on fracture behaviours of the cracked piezoelectric cylinder (a is the radius of the crack and b is the radius of the PZT-6B cylinder).