A frequency-domain variable density downsampling method was applied to the reconstruction of compressive sensing tomography for non-amplifying in-line hologram. The purpose was to extract a small amount of information from the frequency-domain of non-amplifying in-line hologram and realize the reconstruction of compressed sensing tomography from a small amount of data in the frequency-domain of the hologram. Here, firstly it introduced the principle of combining three variable density downsampling with compressive sensing tomography reconstruction of hologram. Three kinds of variable density downsampling respectively were radial distribution, spiral distribution and exponential distribution variable density downsampling. Secondly, it carried out simulation and test experiments and analyzed the reconstruction quality of the methods for variable density downsampling combined with compressive holography. By experiments, it could be seen that: (1) three kinds of variable density downsampling could realize the extraction of a small amount of data for hologram in the frequency domain; (2) with the increase of sampling rate, the compression sensing tomography reconstruction quality of a small amount of data obtained by variable density reduction sampling was continuously improved; (3) under the sampling rate of less than 50%, exponential distribution downsampling had higher reconstruction quality than the other two methods (for example, in the case of low downsampling rate of 15%, the reconstruction quality of exponential distribution was more obvious than the other two methods); (4) under the sampling rate of more than 50%, the tomographic reconstruction quality of the three downsampling modes was relatively high and basically consistent.