The loading technology of microcontroller circuit was used to change the spatial distribution of relative permittivity and relative permeability in different time, the metamaterials spatial filter can be tuned in frequency. A square loop metamaterial filter was designed with unit structure size of 18.5 mm×18.5 mm, which can be continuously tunable in the X band by loading varactor diode on the unit structure. When the varactor diode increases from 0.15 pF to 0.70 pF, the simulation results show that the center frequency of the filter is decreased from 11.8 GHz to 10.5 GHz, the bandwidth is 16.3% (10.2~12.0 GHz), and the return loss minimum is 22 dB, the insertion loss maximum is 0.6 dB. The measured results show that the center frequency of the filter is decreased from 11.7 GHz to 10.3 GHz, the bandwidth is 17.2% (10.1~12.0 GHz), and the return loss minimum is 25 dB, the insertion loss maximum is 0.5 dB.