The present work is mainly focused on the design and analysis of a parabolic spring for a C2 unit truck. This type of suspension offers great advantages compared to a conventional semi-elliptic spring, because, in the new design proposed in this work, an important contribution is to be more efficient, since its parabolic profile offers a distributed effort throughout the spring. This provides efficiency in the use of material. The present work focuses on the optimization of the design applied to vehicle suspension springs. The traditional method for design needs repeated fatigue tests according to its geometry, material and operating condition; this means that a lot of time and money are needed for those tests. Therefore, in this paper, a design method for the spring based on numerical analysis with analytical comparison is proposed; at first, a static analysis is performed to obtain the stress and deformation which are caused by the operation load, as well as a fatigue analysis to obtain the service life and ensure the safety; finally, the five vibration modes are obtained.