A Rankine cycle system is used for collecting waste heat of an engine exhaust pipe. The Rankine cycle system comprises a working medium box, a pressurizing device used for outward extracting working media from the working medium box, a heat exchange device used for conducting heat exchange with the engine exhaust pipe, an energy converting device and a cooling device, wherein the working medium box, the pressurizing device, the heat exchange device, the energy converting device and the cooling device are sequentially connected. The Rankine cycle system further comprises a pressurizing device connected between the energy converting device and the cooling device. By means of the arrangement, the performance requirement for the cooling device and the pressurizing devices is lowered. In addition, the invention relates to a control method for the Rankine cycle system.