Interspecific hybridization between Oncorhynchus mykiss (♀) and Oncorhynchus masou masou (♂) was conducted by artificial propagation.A series of normal stages based on morphological features for the embryonic and larvae development of the hybrid was described.The results showed that the total effective temperature of the embryonic development was 387.44 ℃·d which is higher than Oncorhynchus mykiss and lower than Oncorhynchus masou masou at the water temperature of 4.3-9.2 ℃, while the eyeball pigment stage kept on 206.01 ℃·d;the newly hatched larva was diaphanous all over the body and its blood circulation,heartthrob,anal stylet and dorsal fin rudiment could be seen clearly;20 days after hatching,half of the yolk sac of the larvae was absorbed,the total length was 21.25 ± 1.40 mm,and the dorsal fin,anal fin and tail fin could be seen;40 days after hatching,some of the larvae swam and took in food in the water;45 days after hatching,the yolk sac of the larvae that could swim was absorbed mostly;almost all of the larvae swam up 50 days after hatching.