The invention relates to the technical field of steam generators, in particular to a steam generating unit and a system comprising the same. The steam generating unit comprises a heating channel arranged in a closed shell, wherein the two ends of the heating channel both communicate with the outside world; a first heated unit, a second heated unit and a preheating unit are sequentially arranged in the direction from the inlet to the outlet of the heating channel; water flow channels are arranged in all of the first heated unit, the second heated unit and the preheating unit, and sequentially communicate with one another; and a pressure regulating valve and a check valve are sequentially connected through a pipeline between the preheating unit and the first heated unit. The system comprises the above steam generating unit, the water flow channel of the preheating unit is in pipeline connection with a water supply system, and the water flow channel of the second heated unit is in pipeline connection with a steam treatment system. Compared with a conventional steam generating device which has the same volume as the steam generating unit provided by the invention, the steam generating unit is higher in safety performance.