Abstract: The objective of this study was to determine the effect of warm shed housing on liveweight loss of ewes and on their lambing performance in winter-spring period. One hundred and twenty ewes, from two adjacent local farmers in Taipusi Banner of Xilinguole, Inner Mongolia, were used in winter-spring of 2011, 2012 and 2013. The animals were randomly assigned to two treatment groups: housing in a traditional shed+grazing (TS, control), and housing in a modified warm shed+no-grazing (WS). In summer all animals grazed pasture during the day and were housed in a traditional unheated shed overnight. During winter and spring the ewes in the TS treatment were again grazed on pasture each day and housed in the traditional shed each night, while the ewes in the WS treatment were not sent out to graze during the day. The ewes and their lambs in each treatment were fed the same amounts of supplements of hay and concentrate per day throughout the experiment period. The liveweight loss of ewes in the WS treatment was 22 g/day lower (P=0.005), and their liveweight 1.6 kg higher (P=0.004) at the end of the period, than for sheep in the TS treatment. In all three years the weight loss was greater in December and January than in February and March, and was significantly less (P<0.001) in 2012 and 2013 than in the first year of the experiment (2011). More lambs were born in the warm shed than in the traditional unheated shed (P=0.020), and lambs born in the warm shed also had a higher liveweight (P=0.0005) and daily weight gain (P=0.0001). The lamb weight gain and birth weight were also significantly higher in the later years of the experiment (P<0.001). As the shed temperature increased lambing, survival and twinning rates continuously increased. These results demonstrate that sheep housing in a warm shed during winter and spring will improve animal performance and household incomes and reduce grazing pressure on already degraded grasslands. Importantly, keeping animals in a warm shed in the cold season will assist herders to change from a traditional ‘animal survival’ mind set to a production oriented attitude. Thereby, we recommend sheep sheds should have a thermal time (degree-days)>-40 ℃·d or have an air temperature>2 ℃ during the cold season in pastoral regions of Northwest China.