Abstract: This paper describes the basic parallel control scheme of an oracle relation database system,both in various locks and in sub-tree agreements. By analysing the probferns occured in parallel control sharing data,we have provided an approach to avoid deadlock.In a final Part,we have presented an efficiency test methods,and pointed out the results of our research. Efficiency increased when number of user increased from one to five,and decreased when number of user increased from five to fourteen. Especially, we have proved the efficiency decreased very fast when the number increased from eight to fourteen.