This paper attempts to determine the reasonable height of Vierendeel truss. For this purpose, both analytical and finite-element methods were adopted to investigate how the structural height affects stiffness and global stability. The results show that the structural stiffness of Vierendeel truss varied significantly with the height, peaking at the reasonable height; the global stability changed slowly with the height. On this basis, the authors put forward the formula of reasonable height for engineering design of Vierendeel truss. The results provide a reference for designers to optimize the stiffness and stability of Vierendeel truss.