乙酰胆碱酯酶（英语：Acetylcholinesterase，简称为AChE，EC3.1.1.7）是一种降解（通过其水解活性）神经递质乙酰胆碱成为胆碱和乙酸的酶。该酶主要存在于神经肌肉接头与胆碱能神经系统中，在这些地方该酶的活性就是为了终止突触传递。乙酰胆碱酯酶具有极高的水解活性——每秒钟一分子的乙酰胆碱酯酶可以水解25000分子的乙酰胆碱。经乙酰胆碱酯酶作用而产生的胆碱被重新利用——通过重摄取被转运进入神经末梢，在那里被重新利用以合成新的乙酰胆碱分子。

Acetylcholinesterase (HGNC symbol ACHE), also known as AChE or acetylhydrolase, is the primary cholinesterase in the body. It is an enzyme that catalyzes the breakdown of acetylcholine and of some other choline esters that function as neurotransmitters. AChE is found at mainly neuromuscular junctions and in chemical synapses of the cholinergic type, where its activity serves to terminate synaptic transmission. It belongs to carboxylesterase family of enzymes. It is the primary target of inhibition by organophosphorus compounds such as nerve agents and pesticides.