Abstract: The determination and the calculation of genetic linkage relation of three pairs of genes have always been difficulties in genetics course. To solve the problems, the author found a concise way--searching the gene of dominant or recessive changes in the two most similar phenotypes within test cross progenies of three-factor heterozygote. Result showed that it was easier for the students to study.

Key words: the genetic linkage relation of three pairs of genes, determination, calculation, concise methods