The solution concentration sensor based on microring resonator(MRR)is designed. Firstly, the structure of an all-pass MRR and operating principle of MRR concentration sensor are introduced. Then the eigenvalue equation of 2D slot waveguides is obtained on the basis of electromagnetic field theory and the resonance wavelength of MRR is accordingly calculated. Finally, the transmission spectrum of MRR for ethylene glycol is simulated on the influence of surround refractive index change. The simulation results show that the relation between the resonance wavelength in the MRR and the different concentrations of ethylene glycol solution is approximate linear, which agrees with the theoretical results. The sensitivity of the sensor is around 490.2 nm/RIU. The sensor proposed in this paper has the advantages of low cost, simple structure and high sensitivity, and it can be integrated with the microfluidic optical devices. The proposed sensor can not only be used to measure solution concentration, but also can be used to measure the concentration or the refractive index of solid, gas and other parameters.