The collapse of the tailing dam in the Laochang Pb/Zn mine of Yangshuo, Guangxi province led to the spread of mining waste in Sidi village at karst area along the irrigation river. 31 samples along the contaminated irrigation river were analyzed for total zinc, total lead, total copper, pH, soil organic carbon, total nitrogen, available nitrogen, available phosphorous, C/N and cation exchange capacity in surface soil to assess the soil pollution level. Moreover, the method of canonical correspondence analysis (CCA) was employed to reveal the relationships between soil and environment. The results show that the Pb/Zn/Cu mine of the tailing sand is a multi mineral orebody. Though after almost 40 years farming, the soil organic carbon is still quite low. From the canonical correspondence analysis map, it will be found that the total lead, zinc and copper has the high correlation and the normalized total heavy metals has the positive correlation with the soil organic carbon. Moreover, under the effect of mining water, the karstic soil has to decrease the soil pH, which leads to this area with acid environment character. Then, the soluble P and Pb is easy to generate the low solubility of chlorine (hydroxyl) lead phosphate salt compound, because the available phosphorus has the negative correlation with total lead, zinc and copper, which means that the environment is an important factor to control the reaction process of P-Pb-Zn-Cu. At last, the non point source pollution caused by the Pb—Zn mine tailing will produce many uncertain factors to harness the heavy metal pollution at karst area.