Abstract: The Baikouquan oilfield in Junggar basin has faced with high water cut stage. In such waterflooding process, determination of water allocation quantity or injection?production ratio is of great significance for keeping oil production stable, controlling water cut and realizing reasonable and effective oilfield development. Using the formulae for waterflooding characteristic curves, the predicting model for injection?production ratio changing with water cut is established. Comparing with the traditional water allocation calculation method, it is characterized by simple limited condition and wide applied range. By given a future water cut, the suitable injection?production ratio can be determined. Its fewer production data requirement and simple calculation method are particularly suitable for the reservoir or block which has less static and dynamic production parameters. Case study shows that this method could be applied to other blocks in this oilfield