As one of the important performances of microwave sensors, the sensitivity of conventional planar resonator microwave sensors is limited. In this paper, by analyzing the equivalent circuit model of the metamaterial microwave sensor, a method to improve the sensitivity is proposed. Through analyzing two typical sensor structures: Split-ring resonator (SRR) and Complementary split-ring resonator (CSRR), and comparing the sensitivity of the two equivalent circuit models with the same circuit parameters, we found that by reducing the equivalent inductance and capacitance of the resonant element and enhancing the coupling capacitance between the resonant elements can improve the sensitivity of the sensor effectively.