Breeding high-yield wheat varieties performing well in target environment is economically important. This study conducted a mini review of genome-wide association study (GWAS) outcomes on wheat yield-related traits reported in recent years, and performed GWAS in six individual environments to identify major alleles and their candidate genes responsible for wheat yield-related traits in Australia and North China where rainfed farming system is adopted. A panel of 228 spring wheat varieties were used. A double digest restriction-site associated DNA (ddRAD) genotyping-by-sequencing (GBS) protocol was performed to generate single nucleotide polymorphism (SNP) marker data. A total of 223 significant marker-trait association (MTAs) for yield traits, and 46 candidate genes for the major or consistent MTAs were identified. A phenomenon seldom reported in previous studies was that MTA clustered chromosome segments and gene clusters responsible for the trait were found across the genome, which suggested that marker-assisted selection (MAS) or transgenic method targeting a single gene might not be as effective as MAS targeting a much larger genomic region (GR) where all the genes or gene clusters underlying the GR play important roles.