The mini pump having the characteristic dimension of 1~50mm, has been becoming promising fluid machinery with the growing application in aerospace, new energy and agricultural machinery area for its small size. The cavitating flows over cascade having the chord length of 14mm have been investigated in a cavitation tunnel at different cavitation numbers to study the mechanism and scale effects of cavitation at miniature dimension. Based on the analysis of experimental results, it is shown that the cavitation in miniature flow passage can experience several states such as cavitation inception, sheet cavitation, cloud cavitation and super cavitation with the decrease of cavitation number. For the mini cascade cavitating flow, the cavity characteristics are different from that of single mini hydrofoil because of the interaction among the flows in neighboring flow channels. The mass transfer between liquid and gas phase caused by cavitation for mini cascade is less intense than that for single mini hydrofoil. Thus, there is no large scale cavity shedding in cloud cavitation period in mini cascade. Also, the cavity shape of mini cascade appears thinner and longer at different cavitation states and cavitation development is also hysteresis.