On the basis of introduction to the hologram record and reconstruction, the analysis of particle hologram is carried out for the bubble fields of foam-devolatilzation (foam-DV) in cyclohexane/PDMS system. The effects of the operating vacuum, the initial cyclohexane concentration and the liquid height on the number-average bubble sizes are discussed emphatically. The results show that the number-average bubble sizes increase linearly with increasing liquid height, the operating vacuum and the initial cyclohexane concentration, but the liquid height is a key factor. The factors affecting the measurement error are also discussed.