The resonant micro-optical gyroscope has advantages in miniaturization and integration compared with other gyroscopes. The back-reflection noise is one of the main optical noises restricting the sensitivity of the resonant micro-optical gyroscope which mainly comes from the coupling points between the waveguide ring resonator and the tail fiber. The model of the back-reflection noise of the resonant micro-optical gyroscope based on the reflection-type waveguide ring resonator is established. The influences of the intensity item and the interference item of the back-reflection noise under the reciprocal system and the nonreciprocal system are analyzed, respectively. When the resonant micro-optical gyroscope system is reciprocal, the intensity item of the back-reflection noise has the same impact on the frequency deviation of the clockwise and the counter clockwise lightwave which counteracts, so it has no impact on measuring the rotation rate. When the system is nonreciprocal, the intensity item of the back-reflection noise introduces the noise of the magnitude of 10°/s. The interference item of the back-reflection noise introduces the noise of the magnitude of 257°/s and 261°/s respectively when the system is reciprocal and nonreciprocal. The suppression effects of the back-reflection noise in the resonant micro-optical gyroscope with different modulation techniques are compared. The separation modulation technique can suppress the intensity item of the back-reflection noise when using different modulation frequency and the interference item of the back-reflection noise can be suppressed below the shot-noise limited sensitivity when the carrier suppression reaches 120 dB which is achievable using four phase modulators. The reciprocal modulation technique can improve the reciprocity of the resonant micro-optical gyroscope and can suppress the residual intensity modulation noise of the phase modulator and the frequency noise of the laser effectively. When using the reciprocal modulation technique, the interference item of the back-reflection noise can be suppressed by carrier suppression but the intensity item of the back-reflection noise can not be suppressed which brings the noise of the magnitude of 10°/s according to the simulation result. So it is necessary to add the optical switch or the pulse modulator in the resonant micro-optical gyroscope system to suppress the intensity item when using the reciprocal modulation technique. The optical switch or the pulse modulator can separate the clockwise and the counter clockwise lightwave in time and avoid the energy coupling between the signal light and the back-reflection light which is equivalent to reducing the back-reflection coefficient. In theory, the intensity item and the interference item of the back-reflection noise can be suppressed totally but the suppression effect is limited by the channel crosstalk of the optical switch or the pulse modulator. According to the simulation result, the intensity item of the back-reflection noise can be suppressed below the shot-noise limited sensitivity when the crosstalk of the optical switch or the pulse modulator is 45 dB. To suppress the interference item of the back-reflection noise below the shot-noise limited sensitivity the crosstalk of the optical switch or the pulse modulator should be better than 115 dB which is difficult to achieve. The above analyses provide the theoretical basis for the establishment of the resonant micro-optical gyroscope system. The resonant micro-optical gyroscopes using the separation modulation technique and the reciprocal modulation technique are established, respectively. The outputs of the two system are tested in 1 800 s. The test results show that the gyro output is stable under the separation modulation system because the intensity item and the interference item of the back-reflection noise are both suppressed. The noise of the magnitude of 10°/s is introduced in the system using the reciprocal modulation technique because the intensity item of the back-reflection noise is not suppressed which is coincident with the simulation result.