NOVELTY - Desulphurization of wet and dry marsh gas involves: pressurizing crude biogas from anaerobic biochemical treatment, and cooling; transferring cooled biogas to wet desulphurization tower, where the biogas comes in contact with desulfurization solution and catalyst and removes impurity of sulfureted hydrogen; (3) separating off the water in the biogas and carrying out dry desulphurization using an amorphous hydroxyl-ferric oxide desulfurizing agent; and (4) converting hydrogen sulfide ion in the solution into elemental sulfur through the oxygen in the incoming air.    USE - For desulphurization of wet and dry marsh gas (claimed).    ADVANTAGE - The method shows large and stable treatment effect, and high recovery rate; is easy to regenerate; shows long service life, ensure the content of hydrogen sulfide in marsh gas; and is environment friendly.    DETAILED DESCRIPTION - A method of desulphurization of wet and dry marsh gas involves: (1) pressurizing crude biogas, from anaerobic biochemical treatment, using a fan, cooling the crude biogas to 25-30 degrees C in water washing tower; (2) transferring the cooled biogas to a wet desulphurization tower filled with filling material, where the biogas comes in countercurrent contact with a desulfurization solution and a catalyst while most of the impurity sulfureted hydrogen is removed; where the desulfurization solution is an NaCO3 solution having concentration of 2-3g/l; and the catalyst concentration is 4 parts per million (ppm); (3) separating off the water in the biogas in a dehydration tower and carrying out dry desulphurization in a dry desulphurization tower, where an amorphous hydroxyl-ferric oxide desulfurizing agent is used for the dry desulphurization; and the sulfureted hydrogen is further removed to below 15 mg/Nm3; entering a biogas cabinet; and (4) transferring the H2S-absorbing rich liquid in a regeneration tank; converting the HS ion in the solution into elemental sulfur through the oxygen in the incoming air, and, in the form of sulfur foam, separating out from the regeneration tank while recycling the desulfurization solution; recycling the sulfur foam as sulfur paste with the aid of steaming.