This article makes an in-depth analysis of different body strength calculation methods using fuzzy logic and evolutionary algorithm by taking the universal flat car body strength calculation as an example. For this study, a more scientific and reliable theoretical basis for the structural strength design and analysis of railway flat car surveying and mapping is considered. If the expansion and contraction of the jack are not synchronised while jacking the vehicle body with a jack when the vehicle is freshly manufactured and maintained, the vehicle body will be in a three-point support state. The 3-point support state will result in permanent deformation if a structure with low torsional stiffness is used. If the structure characterized by small torsional stiffness is adopted, the 3-point support state will produce permanent deformation. The safety factor specified in EN12663 is only 1.15, which shows that the Interim Provisions have the highest requirements for the design of vehicle body strength and the corresponding design cost. From the fatigue strength analysis, it can be seen that the difference between the maximum principal stress and the corresponding allowable stress at the node level with the maximum von Mises stress is high, which is not the dangerous position of the structure. The research shows that there are great differences in the provisions of jacking load in various specifications.