The invention discloses a double functional alkaline ionic liquid catalyst as well as a preparation method and an application thereof. The double functional alkaline ionic liquid catalyst has a structure as shown in a formula as shown in the specification, wherein n is any integer selected from 1-6; and X is any one of Cl, OH, BF4, OAc, N(CN)2 or Im. The double functional alkaline ionic liquid catalyst is high in purity and high in alkalinity, has very good dissolving property, can be circularly used, has double functional groups, can be applied to a carboxyclic reaction or a Knoevenagel condensing reaction as a catalyst and shows excellent catalytic performance.