Abstract: Azolla is an important potential bio-resource, but until now there is no cross breeding for its new variety and still the wild varieties are used in agriculture. Recently we have made efforts on its cross breeding method and some hybrid strains have been obtained successfully. Firstly, we have made sure of megasporocarps vigour after castration. The main standard for identication was the rate of megasporocarps germination and not the rate of their opened floats. Also from positive and negative sexual hybridization we have made sure of influence of parent plant on the quantity and quality of seedlings sprouted. Some parent plants might cause a great deal of albinotic seedling. In the phenomena of missing symbiosis and normal symbiosis with Anabaena within symbiotic cavity of Azolla from those albinotic and normal plants, we found that the chlorophyll combination and the symbiosis induction were controlled by two groups of non-linkage genes. The identification by monoclonal antibody technique also proved that all the symbiosis algae of sexual hybrid offsprings were mould of maternal plants. By using esterase isoenzyme banding patterns, the true hybrids and false hybrids were rapidly and effectively identified. Through comparison between the two in morphology and genetics, we could further recognize the hybrids. Our method could acquire the true stems of hybridizable plant.