Abstract: Temperature of drinking water is one of the main factors affecting performance of piglets but it seldom arouses attention by producers. Inappropriate temperature of drinking water can not only have negative impact on welfare and health, but also increase the occurrence of intestinal diseases, resulting in significant economic losses in large-scale piglets production. It was required to settle the urgent issue on how to provide the suitable drinking water temperature, and explain the relationship between drinking water temperature and piglet performance. The objective of this study is to find out the suitable temperature of drinking water for weaned piglets, and provide the drinking water under a constant temperature for the piglets. An automatic drinking water heating apparatus was developed to provide drinking water under a constant temperature, and this water heating equiped with temperature sensor and temperature controller. It was important to analyze the thermal characteristics of drinking water supply pipeline, in order to obtain the relationship between the indoor air temperature, the volume of insulated bucket and the setting inlet temperature of the drinking water pipeline. This relationship can provide a guidance for the uniformity of drinking water supply pipeline in different indoor temperatures. The experiments were conducted in a large-scale pig house located at Jiangsu, and at three levels of different drinking water temperature (13, 25 and 30 ℃). Each level was repeated 4 times, and 10 heads of weaned piglets (120 heads of piglets in total) were selected for each trial. The average indoor temperature and relative humidity was 21.5 ℃ and 63% in the experiment, respectively. The average daily weight gain (ADG), average daily feed intake (ADFI) and ratio of feed to gain (F/G), water intake, diarrhea rate and morbidity rate (MBR) of weaned piglets in each group were recorded. The frequency and time of various behaviors were also monitored using cameras and digital behavior image recorders in the peak period of drinking and feeding (08:30-09:30, 14:30-15:30). And we randomly selected 12 heads of weaned piglets marked with colorful pen in every test groups. The results showed that: 1) Compared with the control group of drinking water temperature at 13 ℃, the experiment group of 25 ℃ could significantly improve the time and frequency of drinking, and significantly increased the water intake of weaned piglets (P<0.05). 2) The drinking water temperature had no significant effect on the daily consumption of weaned pigs (P<0.05), but the group of 25 ℃ could significantly improve ADG, and reduce F/G (P<0.05). The ADG of 25 ℃ increased by 23.2% compared with the control group of 13 ℃, the F/G of 25 ℃ drinking water group was 14.7% lower than that of the group of 30 ℃ and 13 ℃. 3) Compared with the control group of 13 ℃, the group of 25 ℃ and 30 ℃ could significantly reduce the diarrhea rate by 65.2% and 23.7%, reduce the morbidity rate by 58.4% and 34.0% (P<0.05), respectively. 4) The walking behavior frequency was higher than drinking and feeding behavior, and the group of 25 ℃ was higher than that of the other groups significantly (P<0.05), but the feeding frequency had no significant differences among the three groups. Results of this study provide a theoretical reference for setting a suitable drinking water temperature of weaned piglets and expected to improve animal welfare.