Cultivated soybean originated from temperate regions of China, and has a long history of planting in the country, with rich genetic resources. In recent years, however, the high degree of dependance on imported soyabean is a serious potential threat to the food security in China. Therefore, it is crucial to breed high-yield and high-quality soybean varieties, for which the exploration of genes that regulate major yield-correlated agronomic traits such as plant height and bean size, and the analysis of their molecular mechanisms are highly significant. FRITFULL (FUL) genes belong to the MADS box transcription factor, which play important roles in flowering, growth, development, and fruit ripening of plants. By bioinformatics analysis we found six FUL genes in soybean, all of which had a conservative MADS-box and a relatively conservative K-Box domain, and were mainly expressed in the pod, indicating that the gene family might be able to regulate seed-related traits of soybean. Among them, only GmFUL3b gene was highly expressed in the leaves, indicating that its function might have been differentiated in the process of evolution. In addition, we found that the six FUL genes followed different evolutionary rules. In order to further study their biological functions, knockout mutant vectors of the six FUL genes were constructed by CRISPR/Cas9 technology. Positive clones were transformed into soybean hairy roots for test target verification, and five of them were successfully identified as effective targets. It provided an important theoretical basis for obtaining stable soybean mutant materials and analyzing the function of GmFUL family genes.