A volume grating-based holographic pressure sensor in acrylamide photopolymer has been studied. The pressure sensing response is analyzed using a diffraction spectrum in two kinds of sensor construction methods, i.e., transmission and reflection. In a transmission sensor, the maximum of peak wavelength shifts up to 25 nm under ${1.58} \times {{10}^5}\,\,{\rm Pa}$1.58×105Pa pressure. The linear pressure response range exceeds ${2.0} \times {{10}^5}\,\,{\rm Pa}$2.0×105Pa and the optimized sensitivity is ${4.9} \times {{10}^3}\,\,{\rm Pa}/{\rm nm}$4.9×103Pa/nm. Compared to the reflection sensor, the transmission sensor with large slanted angle can provide a more excellent sensing performance. The linear and reversible peak wavelength shifts confirm the applicability of the holographic pressure sensor. A photopolymer-based holographic pressure sensor is expected to apply in a cheap and visual pressure sensing field. The transmission grating is a significant candidate for developing the holographic sensor. These experimental results can accelerate the development and practicality of holographic optical elements.