The article studied the mercury contamination of paddy soil caused by rive water which was contaminated by waste water from smelting mercury factory.Taking 20 cm deep as a layer with drill,we respectively sampled the control and contaminated paddy soil three layers vertically, which contained 58 samples from control fields and 60 samples from contaminated fields. And then we tested the total mercury contents and available mercury contents. The following results were found: the background contents of total mercury and available mercury in control fields of geological mercury belt were 1.307 ppm and 0.353ppm respectively;the total mercury contents in contaminated fields decreased as the increasing of soil deep,but the available mercury contents had no principle Fthe total mercury contents and available.mercury contents in contaminated fields were much higher than those in control fields respectively, which was caused by using mercury contaminated river water to irrigate the fields and mercury accumulating apparently