This paper discusses the problems of instable combustion, serious slag, outfire in boilers with horizontal concentrated boiler, taking a 410t/h boiler as the sample. Through experimental researches on different adjusting characteristics of horizontal concentrated burners, it is found that the coal air mixture has different characteristics in velocity and concentration when the baffles are respectively left in the centrifugal or centripetal side of the bent pipes, and that the baffles wear pattern also depends on individual installation location. During many cold and hot commissioning tests, the effective height of baffles is regulated and the original refractory belts are replaced to vertical evenly spaced bare-tube wall. After taking the above measures, the significant problems in the boiler are settled and the economics and safety operation performance is improved considerably. Thus the paper can offer certain references for other boilers with horizontal concentrated burners.