To systematically investigate the influence of atmospheric correction on Fractional Vegetation Cover (FVC) retrieval accuracy, this study utilizes two test scenes of GF-1 satellite imagery with mountain coverage ratios of 18.3% (low-mountain scenario) and 99.3% (high-mountain scenario) respectively. FVC is retrieved using apparent reflectance (without atmospheric correction) and surface reflectance (with atmospheric correction) respectively to quantitatively evaluate differential impacts of atmospheric correction across varying mountainous terrains. Comparative experiments reveal that: in low-mountain scenario, FVC retrieval using apparent reflectance remained acceptable, while atmospheric correction improves accuracy by 0.93%. In high-mountain scenario, overall FVC retrieval accuracy declines significantly, with coefficient of determination decreasing over 10% and Root Mean Square Error increasing beyond 50% for both corrected/uncorrected data, though atmospheric correction still provided 2.7% accuracy improvement. The results quantitatively demonstrate that atmospheric correction consistently enhances FVC retrieval precision, particularly proving essential for high-mountain areas to ensure reliability. These findings provide empirical evidence for prioritizing atmospheric correction in mountainous remote sensing applications.