Occipital Pool Cyst 2.3*1.7cm is a benign arachnoid cyst, when the occipital pool appears enlarged and appears to have an arachnoid-formed cystic wall with cystic fluid containing cerebrospinal fluid, it is called an occipital pool cyst. The occipital pool is located in the posterior cerebellar fossa and is a normal physiologic cavity. Occipital pool cysts are usually congenital, due to abnormal accumulation of cerebrospinal fluid and abnormal development of the neural tube in the embryo, which causes abnormal development of the subarachnoid space in the embryo and the formation of poorly draining cystic pockets, which gradually form occipital pool arachnoid cysts. It can be detected in cranial CT or magnetic resonance imaging (MRI) examination, and the occipital pool cyst is 2.3*1.7cm. Generally, there is no need for treatment, and it needs to be reviewed regularly to observe whether there is any growth and expansion as well as whether there is any compression of the local tissues and nerves.