Abstract: The uncertainties in all-composite lattice truss core sandwich structure by integral forming process were quantified by an interval vector and the interval analysis model of flat crush resistance of lattice truss core sandwich structure was established. Considering the fuzziness in failure criterion of the structure, analysis and optimization models of fuzzy reliability containing interval parameters were constructed in two different cases: one was with the consideration of design tolerance induced by the production process and the other not. The results show that uncertainties in materials and structures, especially design tolerance, had great impact on the flat crush resistance of all-composite lattice truss core sandwich structure. Not only uncertainties in materials and external loads, but also design tolerance ignored in conventional uncertain design methods, should be considered fully in optimization of lattice truss core sandwich structure. The organic combination of the theoretical result and engineering application achieved in this paper presents an effective method for the analysis and optimization of flat crush resistance of all-composite lattice truss core sandwich structure in engineering.