Abstract: Many applications of TZP ceramics involve prolonged contact with water and/or its solutions. However, until now the wear mechanisms of TZP ceramics under water lubrication has not get the unanimous understanding. The tribological properties of TZP ceramics under water lubrication sliding against 52100 steel have been investigated, and the wear mechanisms of TZP ceramics under water lubrication have been summarized in its wear map. The results obtained indicated that the dominant wear mechanisms of TZP ceramics under mild wear conditions is plastic deformation, whereas under sever wear conditions it is surface fracture. In the transition region, TZP ceramics undergo microploughing and microcracking. The mild and severe wear mechanisms of 52100 steel are plastic deformation and abrasive wear, respectively.