Horizontal curves have been recognised as a significant safety issue for many years, a more important factor than road width, vertical clearance or sight distance. This study investigates the issue of speed selection through curves from several different perspectives. The relationship between safety and curve speed in SiChuan provinces was analysed using data from the local crash database. A sample of curves was selected and surveyed. Following this, acurve treatments for controlling Curve speed for different vehicles was developed based on many factors that has influence on safey.