Abstract: In view of current heavy work of running and pulling and allocating in separate and cyclic water injection, the research on technology of automatically shifting inter-layer separate and cyclic water injection in injection wells is conducted, the downhole automatic cycle switch which is powered by high temperature battery and controlled by a single-chip is developed. The automatic procedure of each cycle switch is set before running, and the automatic cycle switch automatically turns on and off followed the procedures in the downhole, realizing separate and cyclic water injection. The downhole water injection layer can be temporarily changed as needed by marking "low - high - low" hydraulic pressure code according to specific ground time to control the on and off of the automatic cycle switch. This technology has the dual function of automatic control and hydraulic control, allowing separate and cyclic water injection without the need to trip conventional running and pulling or measuring and allocating instrument. Moreover, the short 3-bit hydraulic code realizes easy control and flexible operability.11 wells have been finished, making a breakthrough in intelligent separate and cyclic water injection.