Soil erosion is one of the primary environment problems in today’s world, and 137Cs tracing technology is a mature method in studying soil erosion. It is vital to confirm the reference 137Cs inventory. The paper, giving a new method for determining the reference 137Cs inventory of soil in the region where lacks the perfect reference sample sites, studied the characteristic of 137Cs soil profile distribution and the increase of the number of the soil samples, by comparing with the other’s studies, the determined soil reference 137Cs inventory was 1 820.36 Bq/m2 in Jurong region, Jiangsu Province. This reference inventory was close to the value nearby Jurong region in Jiangsu Province, so the activity was reliable and may be used to estimate the loss rate of soil and the load of agricultural non-point contamination.