When a network system with a weak network structure or an island formed after a system is decomposed, a relatively large frequency fluctuation may occur. As the main component of the dynamic load of the power system, it is particularly important to consider the frequency characteristics when modeling an induction motor. Based on the mathematical model of induction motor, this paper considers different load characteristics such as constant mechanical torque, constant mechanical power and variable mechanical torque. Taking into account the frequency change, the expressions of rotor slip, active power and reactive power of the induction motor are obtained by analytical method. When the induction motor's stator inductance, rotor inductance, magnetizing inductance and rotor resistance change amplitude are ±30% respectively, the influence of load characteristic parameter changes on the active power and reactive power absorbed by induction motor at different frequencies is analyzed. Using Matlab to establish the fifth-order electromagnetic transient simulation model of induction motor, the influence of induction motor parameter changes on load characteristics is simulated and analyzed. Comparing theoretical calculation results with simulation experiment results, the accuracy and effectiveness of the proposed method are verified. This work is supported by National Natural Science Foundation of China (No. 51367009).