An axial adjustable common-path interferometric phase imaging system with simple structure is proposed based on the theory of interference imaging. In this design, making full use of the reversibility of the optical path and the reflection and refraction characteristics of the splitter prism, the incident beam is split into two parallel beams by a prism. One beam is incident on the sample and reflected by the reflecting stage as object light, and the other beam is directly reflected as reference light. The interferograms can be captured by combining object beam with reference beam through the same beam splitter. The interferometer can achieve different types of interference by adjusting the angle between the layer of the beam splitter prism and the optic axis. Taking Fourier transform and three steps phase shift norm method as examples, the phase of the interference fringe is recovered, and the performance of the system is evaluated by the analysis of the results. The feasibility of the proposed design for biological cells phase imaging is demonstrated. The system has the characteristics of simple structure, easy operation and low system error, which can provide an easy and simple method for label-free morphological detection of homogeneous cell.