Preparation method of imidazole type ionic liquid

The invention discloses a preparation method of imidazole type ionic liquid. The imidazole type ionic liquid has the following structural formula: Q X , wherein Q refers to an imidazole type onium cation, and X refers to an anion. The preparation method comprises the following steps: a. carrying out reaction on imidazole or substituent imidazole to produce corresponding salt containing the imidazole onium cation and a carbonic ester anion; b. carrying out anion exchange on the imidazole type ionic liquid containing the carbonic ester anion, and inorganic or organic acid to produce the imidazole type ionic liquid containing the X anion. The halogen-free high-purity ionic liquid can be conveniently obtained by using low-cost carbonic ester to salinize various tertiary amines and quaternary ammoniums and then carrying out ion exchange with a target anion.