In the working process of MEMS capacitive devices, the capacitor plates are usually not in the very opposite position but in an inclined position, which will induce the fringing field effect and cannot be ignored. Based on conformal mapping transformation and complex function correlation theory, the fringing effect model is proposed by inheriting the traditional models and modifying them. Compared with the traditional Heerens’ and Huang’s model, the proposed model is better because the error between the proposed model and the finite element simulation, which is from 10% to 20% when the capacitor plate is moved from perfectly aligned to completely misaligned, is less than that between the traditional Heerens’ s and Huang’ s model. Furthermore, according to the proposed model, when the plate coincidence degree is lower than 40%, the fringing effect increases rapidly. As a result, the proposed model should be applied to correct the capacitance. All above are verified by a digital experiment concerned with MEMS differential capacitor array. The research is helpful for the design and performance analysis of capacitive MEMS devices.