Abstract: Hydraulic hammer is an efficient, energy saving and environmental protection pile penetration construction machine. With the continuous development of China's modernization, the application range of hydraulic hammer is more and more extensive. We analyze the development of hydraulic pile hammer, and expound its working principle. The working principle, oil circuit and hydraulic system of hydraulic hammer are systematically analyzed and studied. The composition and working principle of typical hydraulic hammer which is applied widely in engineering are analyzed. Through learning and absorbing foreign advanced technology, the research can provide technical reserves for the development of domestic hydraulic hammer.