In 2015–2017, with an aim to understand effects of steel slag application to field on soybean yield and soil properties, we used four groups steel slag, 0(CK), 900, 1 200, 1 500 kg/hm2, to fields, which were applied the same amount of nitrogen, phosphorus and potassium. The measured indexes included soybean yield and its components, soil bulk density, total porosity, pH, CEC and the contents of alkali–hydrolysis nitrogen, available phosphorus, available potassium, available silicon and heavy metals in the red soil upland. The results showed that application of steel slag was in favor of soybean yield, with increment by 7.89% at average and the treatment of 1 200 kg/hm2 steel slag obtaining the highest yield. Meanwhile, soil total porosity, pH, CEC, and the contents of alkali–hydrolysis nitrogen, available phosphorus, available potassium and available silicon in upland red soil were significantly increased. The contents of heavy metals Hg, Pb, Cr, Cd and As in soil and soybean were still in the range of the soil environmental quality standards (GB 15618–1995) and national food hygiene standards (GB 2762–2012).