The spatial pattern of natural hydrochemistry features of the rivers in Gansu Province and its controlling factors are analyzed based the water quality monitoring data from 108 main rivers and 128 stations for near 60 years. It is found that the natural hydrochemistry spatial pattern of the rivers in Gansu Province can be divided into Qilian Mountainous area, Gannan plateau area, Loess Highland arid area, Loess Highland semi-moist area and Longnan moist area, of which the main ion concentration is close to each other. The weighted average main ion concentration of the rivers in the province is slightly higher than that of the Yellow River basin, but is higher than that of the Yangtze River basin obviously. Among the main ions, Cl^-or Na⁺ has the maximum spatial changeability, while, HCO₃^- or Ca₂⁺ has the minimum space changeability. Runoff depth, a synthesis factor that reflects the climate change, controls the hydrochemistry features change. Between the main ions and runoff depth there is a remarkable relativity, specially, when the runoff depth is less than 120 mm. When the runoff depth is more than 120 mm, the relativity is not remarkable. The dominant ion will shift in the runoff depth ranging from 5 to 46 mm, depending on runoff depth change, displaying a changing regularity with runoff depth.