Abstract : This paper presents, stress analysis of a ladder type low loader truck chassis structure consisting of C-beams design for application of 7.5 tonne was performed by using FEM. The commercial finite element package CATIA version 5 was used for the solution of the problem. To reduce the expenses of the chassis of the trucks, the chassis structure design should be changed or the thickness should be decreased. Also determination of the stresses of a truck chassis before manufacturing is important due to the design improvement. In order to achieve a reduction in the magnitude of stress at critical point of the chassis frame, side member thickness, cross member thickness and position of cross member from rear end were varied. Numerical results showed that if the thickness change is not possible, changing the position of cross member may be a good alternative. Computed results are then compared to analytical calculation, where it is found that the maximum deflection agrees well with theoretical approximation but varies on the magnitude aspect. Keywords - Stress analysis, fatigue life prediction and finite element method etc.