Hemifacial spasm is a hyperactive cranial nerve disease mainly characterized by unilateral facial muscles paroxysmal, involuntary, irregular and clonic convulsion. Standard microvascular decompression is currently the most effective solution. During operation, it is pivotal to conduct a sharp dissection of arachnoid membrane around the caudal cranial nerves and facial, auditory nerves for fully exposure of pontomedullary sulcus, and lateral pontine region. In this article, the authors demonstrate a hemifacial spasm patient who underwent microvascular decompression successfully in their department. But the authors encountered a serious barrier to the exploration of facial nerve and its offending vessels before decompression and found that posterior inferior cerebellar artery tightly adhered to petrous bone and closely attached to a petrosal vein on cerebellar surface at the same time. The petrosal vein was also seriously stuck to petrous bone. To solve this practical difficulty, the authors employed sharp point knife blade and microsurgical scissors boldly to separate posterior inferior cerebellar artery from the dura mater of petrous bone bidirectionally and bipolar coagulation for effective hemostasis. And then the authors moderately dealt with the surface adhesion of cerebellum for smooth exploration instead of processing the petrosal vein attached to petrous bone because the authors did not want to sacrifice this vein. Relative to the routine microvascular decompression for hemifacial spasm, treatments of the adhensions before decompression were the key technology of this operation.