In a Re-entrant fiber optic gyro(Re-FOG),parts of the two counter-propagating lights re-enter the Sagnac sensitive ring(SSR).Re-FOG is a new kind of fiber optic gyro(FOG),which may lower the error induced by thermal and stress by using a shorter SSR.In this paper the practicality of Re-FOG is studied.A signal detection method which modulates the phase with a serial of pulses is presented and a communication interface is introduced.The experiment results show that the signal detection method can separate the signal of different number of recycling and get the rotation speed of the Re-FOG,the data transfer between Re-FOG and navigation computer can be accomplished fastly,smoothly and precisely.It is clear that the Re-FOG is practical,if some improvements are achieved.