Abstract: With the rapid development of microfluidics, microflow has become an important research area of fluid mechanics. Microcavity is a common type of microchannel structure in microfluidic systems. To elucidate the fluid transport behavior between microchannels and microcavities, as well as the characteristics of laminar vortices in long microcavities, high-speed dye photography and Micro-Particle Image Velocimetry (Micro-PIV) experiments were conducted. The experimental results show that at the Reynolds number Re = 46, an O-shaped flow pattern appears in the microcavity. At Re ranging from 58 to 93, a hook-shaped vortex pattern emerges, accompanied by a U-shaped pattern in the deep region of the cavity. The findings indicate that there is a direct convective transport behavior between the main flow in the microchannel and the laminar vortex. Meanwhile, at Re = 66, primary and secondary vortices occur in a long microcavity with an aspect ratio e = 2. The velocity at the microcavity entrance exponentially decays and becomes nearly zero in the deep region. Unlike the multiple-vortex series observed in macroscale cavities or numerical simulations, at most two vortices occur in the long microcavity in the experiments. The morphological characteristics of the vortices are determined by the Reynolds number and the aspect ratio. The results can provide theoretical guidance for the design of microfluidic devices and offer valuable insights for physiological and pathological studies related to capillary sprouting and growth.