The invention discloses a straw gas purifying system, and belongs to the technical field of pyrolysis gas purifying technology. The straw gas purifying system comprises an injector, a settling separation tank, and a spray scrubbing tower; the injector is used for full mixing of high temperature straw gas with washing liquid, and pressurized output; the settling separation tank is used for gas liquid separation and output of a straw gas washing liquid mixture output from the injector; the spray scrubbing tower is used for purifying and separating gas obtained via separation from the settling separation tank; the settling separation tank is arranged below the injector and the spray scrubbing tower; an input end and an output end of the settling separation tank are communicated with the bottom output end of the injector and the bottom input end of the spray scrubbing tower. The process flow of the straw gas purifying system is simple, and the straw gas purifying system is especially suitable for purifying of straw gas from rotary carbonizing furnaces under micro-positive pressure.