By combining the compound paraboloid with free-form surfaces，a small, energy-efficient collimating lens based on LED light source is designed. The optical design is carried on in two parts separately. One part of the light, whose divergence angle between 0o and 20o, is collimated through a spherical cap contracted the divergence angle and a free-form surface. The other part of light, whose divergence angle between 20o and 80o, is collimated through a compound paraboloid contracted the divergence angle and a free-form surface. The results show that, light angle is less than 4o through this complex collimating lens, and the efficiency of light energy utilization is up to 90%, which could meet requirements for light collimation in current distance.