Pilomyxoid astrocytoma is a new identified variant type of pilocytic astrocytoma, and typically locates in the hypothalamic and chiasmatic region. Herein, we reported a nine-year-old boy with pilomyxoid astrocytoma in the cerebellum. MRI scanning showed a tumor involved the cerebellar vermis, tonsil, the forth ventricle and brainstem. It was homogeneous isointensity on T1WI, relative hyper-intensity on T2WI, hyper-intensity on fluid attenuated inversion recovery (FLAIR) images, and uniform enhancement on contrast T1WI. The tumor was sub-totally removed and was proved histologically to be pilomyxoid astrocytoma. Follow-up at the 5th month, MRI showed the residual tumor enlarged at the brainstem. The patient survived 10 months after the operation, and finally died of respiration failure resulting from brainstem dysfunction.