With the problem of inside guide wheel falling-off from west side of tail-end of the running slag conveyor in No.1 unit of Xinhai power generation company, professionals decided to reduce the load and isolate part of the boiler bottom seal to replace the inside guide wheel online. In a pinch, short-time destroying the boiler bottom seal counld be performed. To ensure the safety of staffs and devices, the scheme of operation and inspection was carried out with preliminary adequate planning and preparation. With the well-controlling of operation parameters, the implementation process would be achieved, which could be serve as references for the repair scheme establishment of coal-fires boiler with similar slagging type.