Objective: To discuss the microanatomy of anterior inferior cerebellar artery (AICA) and to provide related microanatomical basis for surgery in the area of cerebellopontile angle. Methods: Twenty AICAs and their branches at both sides in 10 adult brain specimens were observed anatomically and were measured under an operative microscope. Results: The frequency of bilateral AICAs was 95% and double branches on the same side in one case (5%), The frequencies of their branching labyrinthine artery, recurrent perforating artery, subarcuate artery, and cerebellar subarcuate artery were 95%, 80%, 70%, and 5%, respectively. The frequency of AICA formed the AICA loop near the facial nerve root was 90%. The diameter of AICAs was 1.29 ± 0.43 mm (0.56 - 1.87 mm). The AICA loop was closely associated with the internal auditory foramen, and 80% penetrates between facial nerve and auditory nerve. Conclusion: Being familiar with the microanatomy of AICA helps avoid the damage of related arteries in the area of cerebellopontine angle during operation.