Because nature or tap water has the advantages of low cost. fireprotection, no contaminating to the environment and good altemative of mineraloil, the water hydraulics which used nature water as the working media of hydraulics is getting hot again. In this paper, we have introduced in details the advantages and disadvantages of water hydraulics,the key problems to be resolvedin the water hydraulics and the latcst developments of application and research forowater hydraulics at home and abroad.