Abstract: The content of chlorophyll-a not only reflect the water plankton and the distribution of primary productivity, but also the change of content is often used as a basic indicator to measure the extent of eutrophication water. It is useful for monitoring the quality of the water to understand the space distribution features of chlorophyll-a, in order to achieve the timely discovery and make measures to management purpose. The spatial distribution of chlorophyll-a concentration in Zhalong Wetland was useful to water environmental quality. Keqin Lake was located in northwestward of Zhalong Wetland, Xianhe Lake was located in central section of Zhalong Wetland, and Nanshan Lake was located in southwestward of Zhalong Wetland. The three lakes were selected as study area. The correlation was well between the reflectivity of water and the content of chlorophyll. The reflectivity of water could be directly obtained by spectrometer, so it could be used as auxiliary variables in the Cokriging. Based on Cokriging, 48 measured data of the chlorophyll-a concentration were selected as target variable, reflectance as auxiliary variable in Zhalong Wetland. The results of interpolation showed that the chlorophyll-a concentration in southern part of Keqin Lake was low, the value of number was 2.01-5.04 μg/L, and the chlorophyll-a concentration in northern part of Keqin Lake was high, the value of number was 8.13-11.85 μg/L. General trend was increasing from south to north. The chlorophyll-a concentration in central section of Xianhe Lake was the higher. In the three lakes, the chlorophyll-a concentration of Nanshan Lake was the highest, the highest value of number was 20.83.88-23.41 μg/L. The author analyzed the reason of this phenomenon. It was because there were some villages and many cultivated land around the Nanshan lake. Xianhe Lake was the clearest, the bottom of the lake could be seen and the concentration of chlorophyll-a was the lowest; Keqin Lake was grey and the concentration of chlorophyll-a was higher; Nanshan lake was deep grey and the concentration of chlorophyll-a was highest. On the whole, the interference of human factors were serious in southwest of wetland. The results of interpolation were almost consistent to measured data, which reflected the actual situation of eutrophication level of three lakes.