Based on the facts that the earth is getting warmer and the meteorological observing station's air temperature is increasing rapidly,the climate warming and urban heat island effect of Shenzhen city are studied,under the conditions of the rapid changing of observation environment and the absence of a compared observation after Shenzhen became a big city. The results indicate that the climate warming and the urban heat island effect are of seasonality obviously at Shenzhen. There is a difference between day and night,and far more obvious at night than day.