The lattice constants, total energies and densities of states of transition metals Cr, Mo and W in ⅥB group with different crystalline structures were calculated by the total energy pseudopotential plane-wave method. The results show that the order of lattice stability of Cr, Mo and W is , in which bcc structure is the most stable phase, agreeing with the experimental result. The results of electronic structure calculation show that most of the electrons in s state are transferred into p state and part of s state electrons are transferred into d state. These transferences of electrons from s state to p state or d state form stronger cohesion, higher cohesive energy and more stable lattice of heavy metals.