Abstract: In order to improve the throughput of spent fuel batch dissolver and meet the demand of Chinese reprocessing plant with industrial scale, an enlarging design scheme adopting a cage-like solid neutron poison precept was developed on the basis of current batch dissolver. Furthermore, a modeling machine was manufactured, and a set of experimental apparatus was erected for hydraulics investigation. The result shows that bubble compressed air flux as well as its entrance height, liquid phase temperature and steam flux are the prominent factors affecting dissolver circulation velocity, compared with loading, atmospheric pressure and liquid level. Moreover, the circulation velocity increases almost linearly with the logarithmic value of bubble compressed air flux.