Large amounts of communication bandwidth and memory space is occupied to transmit and store digital hologram on account of its enormous data volume.It is necessary to compress the information of digital hologram for effective transmittance and storage.A new method is proposed to compress the information,according to the spectrum character of off-axis hologram.The sampling frequency is reduced by shifting the useful information of digital hologram from high-frequency section to low-frequency section.Therefore,the information is compressed.The experimental results show the presented method is available.