In order to increase the range of pressure transformation ratio of digital hydraulic transformer and realize the smooth adjustment of pressure transformation ratio, a digital hydraulic transformer based on threestates hydraulic cylinders, called threestates digital hydraulic transformer(TS-DHT), was designed. Its pressure transformation ratio could be changed discretely according to natural numbers pattern through combinations of multistage hydraulic cylinders with different operation states. And its structure and realization methods were given. Compared with the digital hydraulic transformer designed by BISHOP and other designers, it made full use of the three operating states of each hydraulic cylinders, making it possible to construct more pressure transformation ratios when the number of hydraulic cylinders was the same, so that the pressure change was smoother. The utilization ratio of hydraulic cylinders and the output fluctuation of hydraulic control unit under two design methods were compared and analyzed. It is shown that the utilization ratio of hydraulic cylinder is higher, the output fluctuation of hydraulic control unit is smaller, and its economy is better if threestates digital hydraulic transformer is used. Moreover, the more hydraulic cylinders are used, the more obvious its advantages are.