Bubble behaviors in the single and cascaded three-dimensional (3-D) pore-throat micromodels were studied at the operating ranging from 0.0007 to 0.0249. It was found that the average size of daughter bubbles decreased with the rising of the pore-throat ratio, length of throat and mother bubble velocity. The variation of the average size of daughter bubbles with capillary number could be scaled with a power law. In addition, the bubble breakup mainly occurred in the first pore-throat structure and the size of the daughter bubbles maintained almost stable.