A new type of re-entry integrate fiber optics gyroscope(IFOG) which can remain the features of low-cost, high-temperature-stability and miniaturization is proposed. By use of the Transition-mode Multifunction Integrated-Optics Chip (TMIOC),it will eliminate the eigen loss caused by the multiple re-entry in fiber-ring. It will reduce the total loss of the light and raise the signal noise ratio. It can realize the high sensitivity FOG system without the semiconductor optical amplifier(SOA).The phase modulator (PM) of the TMIOC is made up of the anneal proton exchange waveguide (APE) which has natural high-polarization feature. The Polarization-mode Splitter (PS) of the TMIOC uses the method of dual-module couple and attains the separation of the two polarization modes. The separation ratio can reach 20 dB. The polarized-mode transition (PT) of the TMIOC makes the conversion of the polarization mode TE and TM with the acoustic-optics mode conversion. The efficiency of the conversion can reach over 99%, and the power of the acoustic is less than 20mW.The items of the device are apt to the longer fiber and the less re-entry times at present . It can meet the demands of the high sensitivity FOG system. The improvement of the device , for example , improvement of the response speed and reduction of the couple loss , will make the device be used in the descendant-FOG with shorter fiber , more re-entry times , miniaturization , high sensitivity and low-cost