Ear-related traits have an important impact on maize yield and general combining ability (GCA) is an important indicator for assessing maize inbred lines. 248 inbred lines of maize and 400 F1 hybrids derived from combinations with 100 lines selected randomly from the 248 inbred lines as the female parents and four elite inbred lines (‘Mo17’, ‘Chang 7-2’, ‘E28’ and ‘Zheng 58’) as the testers according to the NCII genetic mating design were used to study the ear-related traits. The association analysis of ear-related traits and their GCA was performed using 83057 SNP markers. The results indicated that the ear-related traits were significantly different among the genotypes and the environments. The broad-sense heritability of ear length (EL) and ear diameter (ED) were 81.22% and 87.70%, respectively. Combining ability analysis indicated that there were significant differences among females, males and combinations for the two traits. The contribution rate of special combining ability was greater than general combining ability. 34 significant trait-SNP associations were identified using the data of 4 environments (2 locations in 2 years) respectively, and 7 significant trait-SNP associations were identified using the data of best linear unbiased prediction. Each trait-SNP association can explain phenotypic variation ranged from 0.01% to 19.42% and 5 of them had phenotypic variance explained value greater than 10%. The same SNPs of the ear-related traits and GCA were not identified simultaneously. Based on the LD decay distance, candidate genes were identified in the range of the 120 kb upstream and downstream of significantly associated SNP, and 158 genes were obtained. The putative candidate genes were involved in ubiquitin metabolism (GRMZM2G360374, GRMZM2G049568, GRMZM2G178120), β-galactosidase (GRMZM2G178106), serine/threonine-protein kinase (GRMZM2G127050), lysine and histidine specific transporter (GRMZM2G116004). The study provides a reference for the analysis of the genetic basis and molecular-assisted selection breeding of maize ear-related traits and general combining ability.