Abstract: At the top of 220t/h boiler has been problem of gas leakaged and ash leakaged in Baling Petroleum Chemical Company.The characteristic of new plastic film impervious sealing technology and defect of original design were analyzed. After technology was improved, the problem of gas leakaged and ash leakaged were solved, the best effect of environmental protection,energy saving and safe was obtained. This technology by used of specific material and plastic structure design，furnish a new way to resolve the problem of same mediumsize boller gas leakaged and ash leakaged.

Key words: bolier, plastic film impervious, sealing technology, gas leakage, ash leakage