The fatigue strength of type-A frame of electric wheel dump trucks is defined as an interval value due to the fact that the uncertainty of the manufacturing process and operating environment can easily lead to the change of material parameters. In order to avoid the fatigue failure of type-A frame of electric wheel dump trucks under full load downhill turning braking condition due to insufficient section fatigue strength, an analysis has thus been made of the fatigue strength of type-A frame of electric wheel dump trucks based on blind data theory, with its interval value being 142.32~256.86 MPa. Secondly, based on a full consideration of the uncertainties in its design, manufacture and use, it is to be taken as random variables the structural dimensions of type-A frame steel plate in design stage, the welding material parameters in manufacture stage and the key hinge position load in use stage. By adopting Latin hypercube method, the response values of random variables under periodic loads can be obtained by elastic-plastic finite element simulation, with the stress values of type-A frame interval being 95.01~153.50 MPa. By comparison, the interval stress value of A-frame proves to interfere with the interval fatigue strength. Finally, the fatigue reliability function of random variables can be established based on response surface method, with the genetic algorithm used to optimize the fatigue strength of A-frame interval. The results show that the maximum stress of the optimized A-frame is 134.50 MPa, which is less than the minimum fatigue strength of the A-frame, thus ensuring type-A frame fatigue reliability.