In this paper, we study the single tomographic hologram (STH). We first define the STH and analyze the frequency spectrum of the STH containing three projections, then perform the simulation analysis including the digital recording, information separation and numerical reconstruction of the STH, and finally we rebuild an experimental setup to record the single tomographic hologram from three projections. A phase grating with 100 m period is used as a test sample. The reconstructed period error of grating is between 4%-5%. Both simulation analyse and experimental results demonstrate the feasibility and validity of the STH. In the next work, the improvement of the reconstruction quality for single digital tomographic hologram will be discussed.