DDM product as additive for several imported PMMA units is not produced in China, mainly depends on import.In this paper, a new synthesis process of DDM, alkyl sodium sulfate method, was introduced, and the factors affecting the yield were researched.Exptl. results show that, the process is effective, less investment, low cost, obvious economic benefit.Single pass yield exceeds 90%, reaches French patent level; the quality of product fully reaches quality standards