Based on sampling depths, the research environment of the soil in a study area is divided into two parts: the I environment (I-E) and the II environment (II-E). The results of the statistical analysis of arsenic (As) in the soil of the I-E indicates that the statistical characteristic value obey a normal distribution. The mean value of As is close to the world mean value, China and Tianjin City. Also, the contrast between the spatial change characteristics of As of the I-E and the II-E soils showed that the I-E resembles the II-E in the content variety of As. On the other hand, geochemistry methods were applied in the estimation of contaminated extent. The results indicated that the contamination extent of the north of Tianjin City has not been serious.