Abstract: Pseudogenes are sequences of genomic DNA with such similarity to functional genes that they are regarded as nonfunctional copies or close relatives of genes. Homology search of genomic DNA can reveal pseudogene sequences, and some properties of pseudogenes such as population, distribution, and homology family can be examined. Pseudogenes are important resources in evolutionary and comparative genomics and are considered gene fossils, because they provide molecular records of the ancient genes that existed in the genome millions of years ago. Comparison of genes and pseudogenes offers new insights into the evolutionary history of genes and the stability of the genome as a whole, for example, the determination of the natural selection pressure of pseudogenes with Ka/Ks, the relation and the evolutionary distance between species and tendency of pseudogenes and the origin of DNA mutation.