Abstract: The flood peak types provided the premise and foundation for the reservoir operation rules. This paper explained the method of selecting the index of flood peak type. According to the 7 indicators，this paper identifieed the flood peak types by Projection Pursuit based on Artificial Fish Swarm Algorithm. In the Wujiang River Basin，the simply peak type，double peaks type and three peaks type is 28 floods，21 floods and 4 floods，respectively. To further analysis the differences between the double peaks type，four indicators，which differentiated the double peaks type，were used to identified that 11 floods belong to I-double-peaks type and the rest 10 floods belong to II-double-peaks type.