Grassland ecosystem plays an important role in global climate change. Clipping is an effective management practices to realize the rational utilization of grassland resources. However, the responses of grassland ecosystem CO₂ flux to clipping remain unknown. Here, we conducted a 3-year field experiment in a semi-arid typical grassland on the Loess Plateau to examine the effect of clipping on CO₂ flux. Ecosystem carbon dioxide flux components were measured, as well as soil temperature and moisture at the depth of 0-10 cm. The results showed that the seasonal dynamics of CO₂ flux presented a single peak pattern with the highest values in summer and the lowest values in spring and autumn. There was a slight difference in the timing of CO₂ flux peak. During across experimental period, clipping significantly increased soil respiration (Rs) by 17%, but had no significant effects on the gross primary productivity (GEP), ecosystem respiration (Re), and net ecosystem carbon absorption (NEE). The GEP, Re, and NEE in normal rainfall year (2014) were higher than those in dry year (2015). The response of the GEP and the NEE to clipping depended on rainfall type. There was a significant increase of the GEP and the NEE in dry year after clipping, while an opposite trend was found in normal rainfall year. These results suggested that CO₂ flux were mainly determined by the inter-annual rainfall in the semi-arid grassland ecosystems, and clipping could increase the soil CO₂ emission.