To resolve the problem that the discharge of some wastewater does not come up to the standard in Dagang Kongdian Oi-l field, analyzing the cause that the discharged water did not come up to the standard. The results show that the source of the discharged water from the produced water, contained a large quantity of the suspended solid, oil and other substances, The treating process had some effective measures in eliminating oil and suspended solid, but some main index COD_Cr did not come up to the standard. A new and economical treatment is provided to add adjusting chemicals in process and it makes the water quality come up to the standard and will be utilized in Kongdian Oi-l field.