The invention discloses a marsh gas tank and a heating system of same. The heating system includes a control system, a heat exchange system, and an auto-excitation system. The auto-excitation system includes a combustion chamber being communicated with the marsh gas tank through a gas pipe. The heat exchange system includes a discharge pipeline, a reflux pipeline communicated with the discharge pipeline, and a heat exchange device. The combustion chamber is communicated with the heat exchange device through the pipeline. The control system is respectively connected electrically to the heat exchange system and the auto-excitation system and can control the heat exchange system. By means of the structure, a circulating fluid in the heat exchange system is heated timely by means of marsh gas in the marsh gas tank, wherein the heat is carried into the marsh gas tank for increasing temperature of the biogas slurry in the marsh gas tank; in addition, with the marsh gas, which is produced in the marsh gas tank, as a heat source, the marsh gas tank can be heated continuously, so that a problem of reduced productivity of marsh gas due to excessive low temperature in winter or in night in a marsh gas tank in the prior art can be solved. The heating system has simple structure and is more convenient to use.