Abstract: 【Objective】 The combining ability and their application potential of main agronomic traits of maize inbred lines bred by foreign seed companies were analyzed to provide reference for scientific introduction and rational utilization of maize germplasm resources. 【Method】 Using Xian 21A，SP221，Gui 39722 and Guizhao 18421 Guangxi major inbred lines as test species in breeding，the genetic mating design of 4×22 NCⅡ was used to analyze the combining ability，genetic effect and application potential of 10 important agronomic traits such as plant height，ear height，ear length，ear diameter and kernel row number in 22 maize inbred lines. 【Result】 The results showed that，among the 22 inbred lines，B1， B8 and B22 inbred lines had better general combining ability（GCA）performance for most important agronomic traits. The GCA of different inbred lines had their own characteristics. The bicyclic lines derived from Tieling Vanguard Seed Research Co.，Ltd.（TVD）and Sanbei seed Co.，Ltd. maize varieties had higher GCA of ear length and ear diameter. The average GCA effect values of maize bicyclic lines coming from China Seed International Seed Co.，Ltd.（CS）was higher for the ear row number，as well as the 100-kernel weight of Sanbei Seed Co.，Ltd.，and kernel row number and kernel rate of TVD. Except plant height and ear height，the best specific combining ability（SCA）effect values of other agronomic traits belonged to T1×B20 and T1×B15 among different hybrid combinations.The broad heritability and narrow heritability of plant height were 94.45% and 63.72% respectively，and the narrow heritability of other 9 agronomic traits was less than 50.00%. According to their combining ability，the heterosis groups were evaluated to determine their application potential in breeding. B12，B13，B15，B19，B22 inbred lines selected by TVD and T2（Gui 39722，female parent of Guidan 0810）were in the same group. The inbred lines selected by other companies and the 4 Guangxi major inbred lines might be heterosis groups. 【Conclusion】 The inbred lines B1，B8 and B22 had good comprehensive performance of agronomic traits，which can be used specifically for breeding，while the hybrid combinations T1×B20（the bicyclic line of Xian 21A×Zhengda 808）and T1×B15（the bicyclic line of Xian 21A×Xianyu 1173）are of excellent yield related traits，which can be used for variety regional trials as candidate cultivars. In the breeding process，the maize bicyclic lines selected by different foreign companies can be utilized or improved according to their phenotypic advantages in ear length，ear diameter，100- kernel weight，ear row number and kernel rate. In the selection process of inbred lines，plant height should be selected in early generation，while ear height，ear length，ear diameter，ear row number，kernels per row，100-kernel weight，kernel rate and yield per plant should be selected in late generation.