Esterases are mainly categorized into non-specific esterase (nonspecific esterase), lipase (esterase), and choli-esterase (cholinesterase). Chloroacetic acid AS-D naphthol esterase staining solution (CAE method), also known as chloroacetic acid AS-D naphthol esterase (AS-DNCE) staining solution or specific esterase staining solution, the principle is that specific esterase in the cell will hydrolyze the substrate chloroacetic acid AS-D naphthol to produce naphthol AS-D, naphthol AS-D and diazonium salt coupled with the generation of insoluble colored precipitates, localized in the cytoplasm, the reagent is specific for esterase staining, can be used for choli-esterase. The reagent is specific for esterase staining and can be used for specific esterase staining of blood, bone marrow or cell smears, frozen sections.