Abstract: This paper summarizes the methods and preliminary results of the selective cross breeding experiments on the mud carp in order to improve its low temperature endurance.The genetic traits analysis of the hybrid progenies (F1 and F2) with respect to their parental fishes is presented in this paper likewise.The genetic mechanism of low temperature adaptation and the molecular genetic basis of antifreezing character in some fishes are discussed in this paper. Whether the molecular genetic basis of the low temperature endurance in the mud carp is similar to any one of the other fish's adaptative mechanism or not remains a question for further research. Nevertheless, this question should be an excellent research subject in physiological and biochemical genetics of fish.When the problem of genetic mechanism and molecular basis of low temperature endurance in fish is thoroughly solved, the technique of genetic engineering for improving low temperature endurance in some warm water fishes would get its reliable theoretical basis and the effective scheme for this genetic improvement could be established. However,selective cross breeding is still an effective scheme for genetic improvement at present. The defects of long breeding period and a large number of fishponds required for this scheme would be improved by means of quick establishment of the pure lines through asexual reproduction and distinguishing different parental lines that are cultured in the same pond with phenotypic biochemical markers.