To explore effects of different installation locations and different widths of tip winglets on the aerodynamic characteristics of compressor cascades under the condition of transonic incoming flow, the flow fields of seven diffused cascades including the prototype cascade were numerically studied at Ma=0.8. The results show that under the combined influence of various factors, the suction surface tip winglets with different incoming flow attack angles have negative effects in the flow field, and increase the complexity of the flow field. Meanwhile, the pressure surface tip winglets improve the leakage flow and reduce the flow loss. The effect of the tip winglet on the flow field is proportional to its width in both installation positions. The interference or improvement effect of the tip winglet on the flow field is more obvious at positive angle of incidence. Compared with the normal condition, the most obvious effects of the two types of tip winglets can be obtained under the condition of positive 6°. The suction surface tip winglet with a width of 2.0 times of the original width causes 4.17% flow field loss, while the pressure surface tip winglet whose width is 2.0 times of the original width is accompanied by an improvement effect of 10.15%.