A camshaft phaser having a central bolt is provided. The camshaft phaser includes: a stator and a rotor which is connected with a camshaft in a torsion-resistant manner and accommodated in the stator; a front cover and a rear cover respectively set at a front side and a back side of the stator; and a compression spring having a first end buckled with the front cover, and a second end fixed to the rotor, wherein the central bolt is installed inside the camshaft phaser through an opening set on the front cover, and the central bolt is configured with a guide part which is adapted for pushing the compression spring to an accurate position. Therefore, a supporting apparatus for supporting the spring is no longer required to be configured in the camshaft phaser, structure of the camshaft phaser is optimized, and manufacturing cost of the camshaft phaser is reduced.