Abstract: We discussed the optimal path of two kinds of structures:(1)three dimensionalseparable variable viscoelasticity; and(2)truss.we have shown:1) the optimal deformationpath of viscoelasticity(Maxwell material)is linear on(0,T)and only suffers jump discontin-uance at t = T. We also pointed out the mistakes of some previous studies;2) the optimalloading path of a truss (Maxwell material)is an impulsive one。