Based on the longterm data(1964-1994) of a comparison observation between Jinghong city and rurality ,the effects of development of Jinghong city on climate are studied.The results indicate that with the rapid development of Jinghong city,the urban heat island effect is gradually increasing;the rainfall,air humidity,numbers of fog days,sunshine duration,direct solar radiation and global radiation over the city attenuate remarkably,but the sky radiation is increasing gradually.The urban heat island effect is of seasonality obviously,and iss more obvious in dry season than in rainy season,far more obvious at night than day in dry season,far more obvious at day than night in rainy season.