The approximate entropy method is applied to an ideal time series. It is indicated that the method is capable of distinguishing between different structural dynamics and detecting structural dynamics mutation. And then，this method is applied to the observation data of the daily temperature and precipitation of the 740 sites between 1960 and 2000. The results showed that，the approximate entropy distribution of the temperature and precipitation has a characteristic of obvious district distribution，and displays the territorial difference of dynamic structures of climate system. Abrupt climate changes have been detected by the approximate entropy of the annual precipitation and temperature between 1970s and 1980s. The characteristics of the in homogeneity of temporal and spatial distribution of abrupt climate changes and the complexity of climate systems have been demonstrated.