The Qinghai-Tibet Plateau meadow steppe is an important vegetation type in the ecosystem. It is particularly important to accurately assess the carbon source-sink status and carbon storage changes of the alpine meadow-steppe ecosystem. Based on the observation of eddy correlation system, the change characteristics of environmental factors and carbon flux in the meadow steppe on the north bank of Qinghai Lake from 2009 to 2016 were analyzed. The structural equation model (SEM) was used to analyze the regulatory mechanism of environmental factors on total primary productivity (GPP), net CO₂ exchange capacity (NEE) and respiration (Re). The results showed that the daily mean value of NEE from 2009 to 2016 ranged from -2.02 to 0.88 gC m^-2 d^-1, and NEE was negative from May to September, representing carbon absorption. The net absorption of CO₂ in June, July and August of rain-hot period was the strongest, with the average absorption of CO₂ of 39.85 gC m^-2 month^-1 per month, the number of NEE negative days accounted for about 48% of the whole year. It was positive from October to April of the next year, showing carbon release. The net CO₂ release was the strongest in early spring, March and late autumn, November. The daily mean value of Re was 1.69 gC m^-2 d^-1, which was strong in summer and weak in winter due to the influence of seasonal temperature. The ecosystem respiration intensity in summer was about 8 times that in winter, and the intensity in autumn was higher than that in spring. The daily average of GPP was 3.15 gC m^-2 d^-1. With the increasing of light radiation intensity, the photosynthetic productivity in growing season was significantly stronger than that in non-growing season, while it was strongest in summer and stronger in autumn than in spring. According to the interannual scale analysis, the study area was a carbon sink area, and the average carbon absorption intensity in 8 years was 63.51 gC m^-2 a^-1, the highest NEE of carbon absorption in 2015 was -95.80 gC m^-2 a^-1, and the lowest NEE of carbon absorption in 2016 was -30.60 gC m^-2 a^-1. SEM analysis showed that air temperature (Ta) significantly improved Re and GPP, GPP had a very significantly negative response to NEE, and Re had a very significant improvement to NEE. It is suggested that under the background of climate warming and future temperature rise, the carbon sink function of meadow grassland ecosystem in the north bank of Qinghai Lake may be strengthened.