Based on the Mitsubishi MELTAC digital control system(DCS) platform and its own characteristics, to meet the risk control requirements and download quality requirements, we used the risk-list method to verify the risks one by one. Through verification test and downloading experience, DCS online download technology scheme was put forward. The use in Hongyanhe, Ningde, Yangjiang nuclear power project shows that, the scheme solved the problems of long duration, high risk, wide influence, and the online download reliability rate reached 100%.