In the structural applications, the composite material employs a significant contribution in various industrial applications. In this paper, the experimental nonlinear viscoelastic behavior, tensile and flexural strength properties are analyzed in aloevera /hemp/flax natural fiber sandwich laminate composites (NSLC) with the addition of barium sulfate filler. The dynamic mechanical properties such as storage modulus (E′), loss modulus (E″) and damping factor (Tan δ) are analyzed using dynamic mechanical analyzer as a function of temperature and frequency. The homogeneity, crosslink between the fiber and the matrix of the natural fiber sandwich laminate composite samples are analyzed by a cole-cole plot and complex modulus models. The improvement in flexural strength is observed in the NSLC4 sample (138.34 N/mm2), but the addition of barium sulfate affects the tensile strength (28.8 N/mm2). From the dynamic mechanical analyzer, it is observed that the storage modulus (E′) at the glassy region in the NSLC2 sample is 19.9% whereas in the NSLC4 sample it is 15.57%. Further, the addition of barium sulfate filler enhances the loss modulus (E″) by 28% in NSLC4 sample. The NSLC4 sample shows the better homogeneity in the cole-cole plot and high crosslink between the fiber and the matrix is observed from the complex modulus. © The Author(s) 2019.