In order to avoid the excessive warpage deformation of air-conditioner's heat exchanger fins in the expanding- jointing process,a finite element simulation was carried out to analyze the causes of warpage deformation,the deformation of the grooved fin and the groove structures in different locations on the fin.Then,on the basis of orthogonal experimental design,the primary and secondary factors affecting the warpage degree of the fin,including the dimensions of both the fin and the bulging ball,were analyzed,and reasonable parameters for the expandingjointing process were obtained.Finally,the rationality of the parameters optimized by the orthogonal experimental design method was verified through a trial produce and a heat-transfer finite element simulation.The results show that,as compared with the structure and the location of the grooves,the dimensions of the fin and the bulging ball both affect the warpage degree of the fin more significantly,and that the factors affecting the warpage degree are ranked as follows in the decreasing order of their seriousness: the long-axis length of the fin,the long-axis length of the bulging ball,the minor-axis length of the fin and the minor-axis length of the bulging ball.