Homologous chromosome crossing over is part of genetic recombination. Homologous chromosome crossover interchange refers to the exchange of some of the DNA of two chromosomes when they are paired during meiotic tetrad, known as genetic recombination, which is part of genetic recombination. Genetic recombination occurs in diploid organisms and mainly includes the molecular level, the chromosome level, and the chromosome level can be divided into the cross-swapping of non-sister chromatids of homologous chromosomes in meiotic association and the free combination of non-alleles on non-homologous chromosomes. The former is genetic recombination and the latter is structural variation. Genetic recombination can produce new genotypes, leading to the emergence of recombinant traits and the formation of biological diversity. Genetic recombination is an indispensable part of the process of biological evolution and is of great significance to biological evolution, and it can produce new genotypes and phenotypes, but it cannot produce new genes.