Detection of underwater bubbles is one of the key issues of the research of ocean-atmosphere flux exchange. Digital holographic experiment is carried out based on Mach-Zehnder digital holographic system, to detect the distribution of bubbles. Holographic images of the dynamical bubble fields are recorded by the chargecoupled device (CCD) video system and the tomographic images at different depth are reproduced. The distribution of sizes and densities of the bubbles is obtained through following steps as denoising, edgedetection, and bubble-recognition using Hough transform. Through the experiments, the efficiency and applicability of the digital holographic detection of underwater bubble fields are tested and verified.