The invention discloses a measuring method for re-suspension critical stress of submarine sediments. The measuring method comprises the following steps: step I of regulating and arranging an observingdevice and parameters; step II of arranging the observing device; step III of obtaining original data; step IV of pre-processing the original data; step V of obtaining suspended solid mass concentration SSC; step VI of calculating a derivative, on time, of SSC, and determining that a re-suspension event occurs when the derivative is positive and is kept for ten minutes or more, counting re-suspension times and corresponding bottom stress, and determining the re-suspension critical stress of submarine sediments. The observing device for the measuring method comprises a battery bin, an ADCP, anOBS, a CTD and an ADV. The measuring method has the beneficial effects that: a plurality of sets of apparatuses synchronous observe, so that flow speed, echo intensity and turbidity data of a water perpendicular section with a high resolution are effectively obtained; long-time observation and storage is realized, data is continuous and the resolution is high; and in case of not damaging a site environment, changes of mass concentrations of the suspended solids are obtained, so that relatively accurate parameters such as submarine stress and critical stress of a submarine bottom boundary layer are obtained.