The oceanic carbon pool and terrestrial carbon pool are connected by rivers. Carbon dioxide (CO₂) evasion from rivers to the atmosphere represents a substantial flux in the global carbon cycle. The CO₂ efflux (FCO₂) and CO₂ partial pressure (pCO₂) in large rivers have been widely evaluated. Most studies concerning CO₂ emission from the Yellow River, a typical river containing high sediment concentrations, focused on the lower reach and its estuary, but less is known about its upper and middle reaches. In this study, a river cross-section at the Toudaoguai Gauging Station in Inner Mongolia, the dividing point between the upper and middle reaches of the Yellow River was chosen as a study site. Evasion of CO₂ was measured four times each year using Li-7000 static chamber method from 2013 to 2015 at four sampling points in a river cross-section. The spatial and temporal variations of FCO₂ were analyzed. The relevant hydrological indexes, including water temperature, pH,and wind velocity as well as current velocity were measured at the four sampling points. The hydrochemical indicators, including ALK and DOC in water samples, were analyzed in the laboratory and pCO₂ was estimated. The possible influential factors of FCO₂ were further discussed using correlation analysis. The CO₂ evasion from the river cross-section ranged from 14 to 186 mol m^-2 a^-1 and its average was 84 mol m^-2 a^-1. The pCO₂ in the Yellow River at the Toudaoguai Gauging Station was within the range of 467-2101 μatm and the average value was 995 μatm. The concentration of DOC ranged from 2 to 13 mg/L. The FCO₂ exhibited obvious seasonal variations, with the maximum FCO₂ of 456 mmol m^-2 d^-1 occurring in summer and the minimum of 33 mmol m^-2 d^-1 occurring in winter. The FCO₂ values were markedly different at sampling points, with the maximum value of 392 mmol m^-2 d^-1 at S4 near the right bank, similar values at S2 and S3 in the middle of the river section, and the minimum of 86 mmol m^-2 d^-1 at S1 near the left bank. The analysis of factors influencing FCO₂ indicated that FCO₂ was positively correlated with current velocity and pCO₂, and negatively correlated with pH. There was no obvious correlation between FCO₂ and wind speed. Results also showed that current velocity contributed more to FCO₂ than to pCO₂ in the river cross-section. In this study, evasion of CO₂ from the Toudaoguai cross-section was determined on a relatively fine scale. The results suggested that a distinct spatial variation in FCO₂ exists even at the level of river cross-section, with the maximum FCO₂ found at the point with the highest current velocity. Thus, typical sampling points in a river cross-section should be chosen for FCO₂ measurement. The study provided a scientific reference for both FCO₂ evaluation in the upper and middle reaches of the Yellow River and FCO₂ sampling in a river cross-section.