Abstract: The systematic errors among sampling sub-areas caused by difference of sample collection, processing and analysis can greatly distort the prospecting significance of the original geochemical data, which therefore cause great obstacle to recognition and assessment of geochemical background and anomaly. Researches have suggested several approaches, such as Direct Raising, Method of Contrast Coefficient, Method of Standardization, and C-transformation. The primary goal of C-transformation is to strengthen the ore-bearing information of the regional geochemical data. However, the result of this paper demonstrates the feasibility of C-transformation in systematic error correction and transformation applied to correct the systematic error of As among four 1∶200000 standard mappable units. The concrete approach has 4 steps, including: 1) recognize the spatial extension of systematic error, 2) separate the data set into subsets, 3) obtain the radius of moving window on the basis of structure analysis, 4) carry out the C-transformation in each sub-area to gain C-coefficient on each sample location.