Abstract: A tunable transparent liquid-controlled absorbing structure is proposed. This structure consists of double square ring frequency selective surface(FSS) structure, transparent dielectric layer and conductive plate. There are two liquid medium filling layers(an upper and a lower) in this structure. Regulation of microwave absorptivity can be controlled by injecting liquid medium with different electromagnetic parameters; the surface color of the structure can be changed with the injecting liquid medium of different colors; the surface temperature of the structure can be controlled by circulating injection mode and flow rate control of the liquid medium. The proposed structure is expected to be applied to multiband camouflage technology, and it may be the foundation of the adaptive camouflage. This paper mainly studies the law of the influence of different liquid medium injection on the microwave absorption performance. The simulation results show that changing the injection mode and type of the liquid medium can achieve a large reflectivity adjustment of more than 10 dB in the 4-18 GHz frequency band, and the absorption structure has the potential to adjust the optical and infrared characteristics at the same time.