A low cost and efficient damage detection method is developed by introducing a new piezoelectric composite coating combined with a self-powered wireless signal transmission module. The new piezoelectric composite coating composed with a piezoelectric layer, an electrical conductive layer and an insulator, is designed as the sensor and to be easily applied on rough surfaces of engineering structures, such as concrete and the welded joint area. An energy harvesting circuit and an automatic electronic switch controlled by the piezoelectric coating sensor are designed to power and control the wireless signal transmitter sending warning signals of the damage occurrence. Methodology is explained in detail, and successful detection of the occurrence of crack propagation on a beam structure has been realized through experimental testing.