Based on the 35 a collated data of 25 meteorological stations from 1981 to 2015 and the hourly data of 5 regional meteorological stations from 2015 to 2019 in the southwest of Shandong Province, the characteristics of temperature distribution in the southwest of Shandong Province and the contribution of the Nansi Lake to the distribution are systematically analyzed. The results are as follows. 1) The annual mean temperature in the southeast of the district shows a southeast-northwest oriented warm tongue, according with the direction of the Nansi Lake. The Nansi Lake has changed the common temperature pattern of high in the south and low in the north and makes the monthly mean temperature in the southwest of Shandong Province appear as patterns of high in the east and low in the west and transitional adjustment. 2) The Nansihu district is the low value area of the highest temperature and the high value area of the lowest temperature, and the annual mean daily range of temperature is relatively small. 3) Compared with the temperature of the same longitude and the same latitude areas in the southwest of Shandong Province, the monthly mean daily range of temperature and the monthly maximum daily range of temperature in the district are relatively small, the difference in autumn is the most obvious, and the difference in summer is the smallest. The daily range of temperature is relatively stable. The temperature of the district is lower during the high temperature period of the daytime and higher during the low temperature period of the nighttime, and the daily maximum temperature appears about one hour late. Under the same weather conditions, the daily range of temperature in the district is always small, while under different weather conditions, the difference of daily maximum temperature and the difference of daily minimum temperature between the district and the same latitude area are the largest in sunny days, followed by those in cloudy days, and those in rainy days are the smallest.