To clarify the continuous and environmental effects of the amelioration of heavy soda saline soil using desulfurized gypsum, an outdoor pot experiment was conducted to study the growth situation of forage maize, physicochemical properties of the soil, and contents of heavy metals in plants when the soda saline soil was treated with different rates of desulfurized gypsum (0 t/hm2, 15 t/hm2, 22.5 t/hm2, 30 t/hm2). The results showed that the remediation effect of 15 t/hm2 desulfurized gypsum was the best. It could significantly improve seedling emergence rate, plant height, stem diameter, and seedling biomass of forage maize, which was increased by 20.6%, 16.8%, 8.1% and 10.1% compared to the control, respectively. The pH, EC, and the content of Na+ in the soil were decreased, but the contents of Ca2+ and SO42- in the soil were increased. As the amount of desulfurization gypsum was increased, the effect of desulfurization gypsum became more obvious. The content of As, Hg, and Ni in the soil and forage maize roots increased with increasing amount of desulfurization gypsum. According to the second grade of national environmental quality for the soils (GB 15618—1995), the contents of heavy metals (As, Hg, Cd, and Ni) in the tested soil were all complied with the Environment Quality Standard. The contents of heavy metals in the forage maize shoots were not significantly correlated with the application rate of desulfurization gypsum, and the heavy metals contents in each treatment did not exceed the standard limits according to Hygienical standards for feeds (GB 13078—2001). The heavy metal contents in stems were less than those in shoot, and the accumulation rate of heavy metals was in the order of Cd＞Hg＞As＞Ni. It can be concluded that the continuous effects of desulfurization gypsum to ameliorate the soda saline soil were good, and did not show adverse impact on the environment.