The sensing performance of micro-ring biosensor on Silicon-On-Insulator(SOI) was studied through simulation. The sensitivity of 38.71 nm/RIU, detection limit of 1.8×10-3 RIU and Q factor of 2.22×104 were achieved. The effects of noise on the sensor, including the light source noise and temperature noise, were then investigated. A dual micro-ring differential sensor with reference and probe channels was proposed, and the wavelength drift induced by the noises can be deducted to reduce the influence of noise by this differential operation. The relative error of the refractive index change was reduced by 15.85% through the calculation and numerical simulation, so the micro-ring differential biosensor can effectively reduce the influence of noise to enhance the sensing performance of the micro-ring biosensor.