Abstract: China’s terrain is high-lying west and low-lying east with three-step terrain from the west to the east. The landscape patterns are bound to affect the climate elements，such as temperature，humidity，solar radiation，as well as the distribution of tourism climate comfort. Based on the long-term observation of climate data，this paper used the new comprehensive climate comfort degree evaluation model and selected 19 cities near the north latitude 30°N and 35°N lines，referenced the three index classification and valuation standard and calculated the monthly [THI，][WCI，][ICL，]and through the weighted synthesis comfort index classified the comfortable and uncomfortable periods of tourist climate. On the basis of these，this thesis analyzed the relationship between the climate comfort degree and the three-ladder terrain. The main conclusions are as follows：（1） the first influence of the three-ladder terrain to tourist climate is the temperature and the [THI.] Regarding January，April，July and October as the representatives，this paper analyzed the changes of the land surface temperature with altitude and found that temperature differences are large in summer and small in winter. There are temperature differences in spring，summer，autumn and winter，and temperature difference amplitudes increase with latitude increase. （2） The typical months’ temperature and [THI] of the cities take shape the corresponding changes to the three-ladder terrain. Each month’s temperature and [THI] take place sudden changes at the altitude of 3 000 m with the temperature and [THI] differences large in summer and small in winter. （3） The comfortable and uncomfortable periods of tourist climate in the cities appeared abnormal distribution. The comfortable period on the first ladder in the east is about 5 to 7 months and non-comfortable period 4 to 6 months due to the hot summer. The comfortable period on the second ladder in the middle is about 6 to 8 months and non-comfortable period 4 to 5 months. The comfortable period on the third ladder in the west is about 0 to 4 months and non-comfortable period 8 to 12 months due to the elevation of more than 3 000 meters. The relevant reports haven't been seen on the difference between the climate comfort degree and comfortable period caused by topography and three-level ladder. This study reveals some differences of tourism climate comfort degrees between the east and the west of China and the main influence factors. This thesis provides lots of climatology references for macro-tourism development.

Key words: climate comfort degree, 3-step terrain, differences between west and east China, tourist cities