[Objective] Identifying the variations in soil respiration and its influencing factors, to provide the basis for evaluating the carbon sequestration resulting from converting cropland to apple orchards on the Loess Plateau.[Methods] A field experiment was conducted in a mature apple orchard at the Changwu State Key Agro-Ecological Station, Shaanxi, China. Soil respiration, soil temperature, and soil moisture (θ) were periodically measured in situ for three years by an automated soil CO₂ flux system (Li-COR, Lincoln, NE, USA).[Results] Soil respiration exhibited very significant seasonal and annual variations. The highest values for soil respiration were 3.14, 3.98, and 4.71 μmol/(m²·s), which appeared during the rainy season (July to September); the lowest soil respiration value appeared in November, at 0.99, 0.88, and 0.69 μmol/(m²·s) for three years; and the coefficient of variation for the cumulative soil respiration was 21%. Soil respiration and soil temperature followed an exponential relationship, and the soil moisture significantly influenced the soil respiration and temperature sensitivity of soil respiration(Q₁₀) values. Soil respiration was 2.01 μmol/(m²·s) when θ< 11.12%, while it increased to 2.24 μmol/(m²·s) when θ ranged from 11.12% to 23.63%, and decreased to 1.38 μmol/(m²·s) when θ> 23.63%. The Q₁₀ value was 1.57, 1.63, and 1.38 when θ<11.12%, 11.12%<θ<23.63%, θ> 23.63% at the apple orchard.[Conclusions] Soil moisture significantly influences soil respiration and Q₁₀. This study is useful for estimating the soil carbon sequestration in orchard ecosystems on the semi-arid Loess Plateau.