The invention discloses a purification method of converter gas. The method comprises the following steps: 1) air entrainment: pressurizing converter gas after dust removal and temperature reduction, delivering the pressurized converter gas to a temperature swing adsorption unit; 2) temperature swing adsorption: sending to the gas treated by the step 1) to an adsorption bed to remove sulphur, phosphorus and arsenic of the gas through pressure swing and temperature swing adsorption, wherein the adsorbent in the adsorption bed uses activated carbon, silica gel or aluminum oxide as carrier which is loaded with 0.1-15wt% of one or more of the compounds of potassium, sodium, calcium, magnesium, zinc, iron or copper; and 3) fine arsenic removal: sending the gas treated by the step 2) to a fixed bed reactor to perform catalytic absorption and remove arsenic compounds in the mixed gas. The purification method of the invention has clever conception, simple process and low investment and can effectively reduce the contents of poisonous and harmful impurities in converter gas and meet the requirements of chemical production on the raw material.