The present invention relates to a bone dilator designed for treating compression fracture of vertebral body, and fractures of cancellous bones at other sites. The bone dilator comprises a head portion, a neck portion, a connecting tube, a handle and a rotary hilt. The head portion embodies different shapes for use at different locations. When the rotary hilt is rotated clockwise and the pull rod is pulled backwards, the upper and the lower parts of the head portion keep parallel or at a predetermined angle during expanding. When the rotary hilt is rotated counterclockwise and the pull rod is pushed forwards, the head portion and the neck portion completely join together, the distal end of the pull rod and the bar stays are completely or partially retracted in grooves inside the head portion and the neck portion.
