The application of modified spherical phosphogypsum in cement production in South Kalimantan Island, Indonesia was studied. Modified spherical phosphogypsum is an industrial by-product prepared by adding alkaline substances to phosphogypsum and using a ball forming or granulation mechanism. The study focuses on the cement produced in the region, and gradually adjusts the ratio of natural gypsum to modified spherical phosphogypsum based on the gypsum retarding mechanism. Combined with relevant standards, tests were conducted on cement setting time, compressive strength, and other parameters. The experimental results show that the SO₃ content in cement is positively correlated with setting time, but only exists within a specific range. By adjusting the gypsum ratio, the SO₃ content in cement can be reduced to about 1.6%, while maintaining the setting time and compressive strength to meet local demand. In addition, the study also found that it is feasible to use modified phosphogypsum instead of natural gypsum to produce cement in the absence of natural gypsum, and the use of spherical modified phosphogypsum is more effective, with good fluidity and less fluctuation in SO₃ content.