Frequency control is essential to maintain the supply stability and security in microgrid. In islanded mode, energy storage systems (ESS) or load control was often used to solve frequency fluctuations. However, the use of energy storage systems will be followed by a huge investment. Besides, the load control scheme doesn't distinguish importance of load; the load of importance will be greatly impacted. In this paper, an adaptive flexible power electronic loads (FPELs) control method considering the importance of load is proposed, which solves the problem of imbalance between supply and demand, so that the frequency deviation of the microgrid is within the allowable range. In the proposed control scheme, the FPELs are divided into three grades according to importance degree. The control strategy enables load to be orderly involved in supply-demand regulation according to its importance. So, this method reduces the impact on important loads. Frequency as the control signal of load saves communication investment. As a result, the control strategy keeps balance between supply-demand of microgrid. Matlab simulation results show the effectiveness of the control strategy.