The phosphine transverse circumfluent fumigation system for paddy warehouse (with span of 18 m) was designed and the application of the technology in paddy storage was studied. The concentration of phosphine in the grain bulk and the ventilation ducts was detected during the fumigation. The results showed that the concentration of phosphine in the vertical and horizontal cross sections of the grain bulk distributed evenly. Compared with the traditional fumigation in whole warehouse, the concentration of phosphine distributed evenly, and needed less time to reach to the insecticidal concentration by transverse ventilation. The concentration of phosphine could maintain longer in the film sealed grain bulk, which decreased phosphine dosage efficiently.