The invention discloses a transition device for a volute type short distance between an internal-combusting wave rotor and a turbine, and belongs to the technical field of gas turbine engines. The design of the transition device considers an outlet molded surface of the internal-combusting wave rotor, an inlet molded surface of the turbine and the area proportion of the outlet molded surface and the inlet molded surface, and the size of a channel along the way is determined in a mode that an inlet section starts gradual reducing; and a spiral-baseline volute type scheme layout is adopted so that airflow can be distributed evenly in a flowing channel, separating of the airflow is avoided, the flow loss is reduced, and meanwhile, the axial length of an internal-combusting wave rotor engine can be shortened effectively. The transition device is mainly applied to component matching between the internal-combusting wave rotor and the turbine of the gas turbine engine based on an internal-combusting wave rotor technology, solves the problem of transition between the outlet molded surface of the internal-combusting wave rotor and the inlet molded surface of the turbine effectively, moreover, can reduce the axial distance and light the whole weight of the engine, and meanwhile can further be applied to transition areas of other similar rotary machines to achieve similar purposes.