Water is the basis of wetland, the degree of water health directly determines the function of wetland ecosystem. The theory and method of water health were established in the study. Water health included both water status health and water process health. Water status health was reflected by hydrologic condition and water quality. Water process health was calculated by water elasticity, water stability and resilience. Xixi Wetland Park was taken as the case study. The results indicated that: 1) Seasonal variations of water health were apparent in Xixi Wetland. Water health index was the highest (46.36) and stayed under the sub-health condition in summer. In contrast, water health index was the lowest (37.35) and unhealth in winter; 2) the degrees of water health were obviously different between ponds and creeks. Water health index in ponds was 42.72, which was higher than that of creeks (37.99); 3) Water in Xixi Wetland Park was sub-health with 53.80 as its water health index. Based on the result of study, to enhance water health of creeks in winter is an effective measure to improve water health in Xixi Wetland Park.