Abstract: The tank body of an oil truck may account for 12%~24% of the whole vehicle weight. Lightweight design of tank bodies is essential for reducing engine fuel consumption and improving steering stability of trucks. The structure design of tank body made of metal is matured, and it is difficult for further lightweight, because of the high density of metals. Making use of the excellent mechanical properties, low density and the designability of composite materials, a novel lightweight composite tank body was designed and analyzed in this work, considering operations of the truck under multiple road conditions. Firstly, a three-dimensional model of the tank body was established based on the finite element method. The numerical simulations were then conducted to study the stress distribution of the tank body in detail under static and dynamic loading conditions. Modal analyses were then performed to determine the natural frequencies and corresponding vibration modes of a number of fundamental modes, which provides a useful reference for engine selections of the truck. The results show that mass of the composite tank mass is 64.1% less than steel counterpart, and 19.8% less than the aluminum counterpart.