Nowadays oil-bearing wastewater in most oilfields is refilled into underground after treated by hydrocy- clones with its complete reuse technology.The main technical parameters are the concentration of oil and sus- pended solids.So we utilize the two-class hydrocyclone that has been serially connected with the filtering equip- ment or with other complete reuse technology to make purification contrasts.The results are very satisfactory. The optimum design, test and application have been summarized.Combining with the result of the complete technology of various hydrocyclonic treatment and the typical experimental date contrasts, the complete reusing technology which meets the production demands is optimized.It, therefore, set a foundation for the new com- plete technology of water treatment equipment centered on the hydrocyclone and an environmental demonstration base.The economic profit is increased.