High impedance surface, due to its unique property of in-phase reflection at some frequency, could be used in designing multiband Salisbury screen by replacing the metallic ground plane in a traditional structure, which is proposed, in this paper, to enhance the microwave absorbing performance of the conventional Salisbury screen. First, electromagnetic wave field intensity of different frequency in space after being reflected by a high impedance surface is analyzed, which implies that new absorption bands can be introduced at about the frequencies of in-phase reflection by sharing Salisbury screen’s resistive sheet, without adding extra lossy materials such as lumped elements or others. Then, by taking a single band high impedance surface at 6.25 GHz and a dual-band high impedance surface at 6.27 and 8.17 GHz, which are both composed of patches array with varying periodic size and a thickness of 0.6 mm, the multiband Salisbury screens can be constructed utilizing a conventional one with an absorbing peak at about 10.5 GHz. The reflectivity of these multiband absorbers are simulated by employing the commercial CST microwave studio and later measured using a reflectivity measurement system comprising two polarized horns and a vector network analyzer. Experimental results agree well with the simulations, and all results verify that the method presented at the beginning is effective. Results also show that new additional absorptions appear at the frequencies where microwaves are nearly reflected in phase from the high impedance surface, with the same number of the in-phase reflection bands. Meanwhile, the original microwave absorbing capability of the traditional Salisbury screen is reserved mostly. Compared to the single band high impedance surface, the dual-band high impedance surface performs better in the design as the absorbing bandwidth is wider and the absorbing frequency is lower. With an additional thickness of the high impedance surface (no more than 1 mm), the total absorption bandwidth of the multiband Salisbury screen with a reflection below -10 dB increases from 8.5 to 10.1 GHz, and the lowest frequency with 10 dB absorption falls from 7.5 to 5.98 GHz. So it could be concluded that the design of multiband Salisbury screen is helpful to widen the absorption, especially towards the lower frequency direction.