Chronic hydrocephalus，which is a common complication of intracranial aneurysmal subarachnoid hemorrhage，has a signifi－cant impact on function and quality of life. In traditional theory，chronic hydrocephalus is associated with subarachnoid fibrosis. How－ever，recent research has shown that that chronic hydrocephalus is related to osmotic and hydrostatic pressure in micro-vessel of the central nervous system. The influence factors of chronic hydrocephalus are so complicated that no exact measure of preventions and treatment has been found yet. In this paper，we review the recent advances in risk factors，preventive treatments，and new theories of the pathogenesis of hydrocephalus.