The flow field in the tail flue of coal-fired boiler has a great influence on the service life of its equipment. In order to improve the flow field of the flue at end of the boiler and solve the wear and leakage problem of low-temperature economizer tube bundle due to uneven flow field,and study the influence of guide plates with different design structures on the flow field in the system,the flow field in the original system flue was simulated and analyzed based on ANSYS18.0-FLUENT field simulation software. The results show that the velocity of the flue in front of the low-temperature economizer is uneven due to the change of cross section and the deflection of the direction of the flue. Without the guide plate,the standard deviation(Cv）of the cross section of the heat exchanger at Y=1 700 mm reaches to 70.7%,resulting in the uneven flow field of the heat exchanger,which makes the local flow velocity too high to aggravate the wear of the tube bundle. According to the characteristics of the flue,several guide plates with different structural parameters are set at each key position affecting the flow field. Through a series of detailed analysis and comparison of design schemes,it is found that the plate length,spacing and installation angle of the guide plates set at the position of flue direction deflection or section mutation have a significant impact on the flow field. According to the different characteristics of the positions that affect the flow field of the flue,all the structural parameters of the guide plates were optimized and analyzed. The optimal structural parameters of the guide plates were obtained,and the guide plates with excellent performance was designed. After the corresponding guide plates are added at the corresponding positions,the standard deviation of velocity in the heat exchanger area of scheme 1 is 65.1%,and that in the heat exchanger area of scheme 2 is 55.4%,while scheme 3 greatly improves the flow field in the heat exchanger area,and reduces the standard deviation of velocity in the heat exchanger area to 9.6%.The system resistance only increases by 109.8 Pa,meeting the design requirements. The scheme has high practicability and obvious effect,which provides a good theoretical guidance for practical engineering design.