The use of full-length cDNA libraries is an effective tool to obtain complete gene information in a high-efficiency, high-throughput manner, especially in organisms with huge genomes that are not amenable to whole genome sequencing. In this review, we outlined several methods of full-length cDNA library construction and compared their advantages and disadvantages based on their respective principles. Drawing on our own experience, we described the Cap-trapper method in detail, with an emphasis on its application in wheat full-length cDNA library construction as well as the determination of the ratio of full-length cDNA in a library.