Abstract: To satisfy the requirements of reliable Web services, the mechanism of adaptive failure detection for Web Services in the dynamical network environment is studied. A framework of hierarchical failure detection is presented firstly, then an algorithm based on load awareness and checkpoint is designed. It considers the factors including the frequency of messaging delivering and packet loss so as to enhance the adaptability to the network context and to improve the quality of detection. Simulation results show that the algorithm can guarantee the correctness of detection as well as obtain the tradeoff of rapidness.