Caudal block has much advantages such as simple operation,less complications,obvious effect,flat and low anesthesia.For those reasons,caudal block is widely used in pain treatment and clinical anesthesia.The traditional way of sacral canal anesthesia is based on osseous marks.However,because of variable anatomical structure in sacral canal and the sacral horns,the traditional method has many defects.In recent years,as a new operation method,caudal block under the guidance of ultrasound has began to be applied gradually.The advantages,application progresses of this method were reviewed in this paper.