By using the method of first principles calculations based on density functional theory, the mechanical properties and electronic structures are calculated by substituting Ti atoms with V atoms to construct a model of Ti-V system with different V contents by using β-Ti as the research object. The calculation results indicate that the addition of V atoms decreases the elastic constants and elastic modulus of elasticity of β-Ti, as well as the plasticity and toughness of the system can be enhanced. This is because during the formation of the Ti-V system, both atoms lose electrons which the electronic mobility of the system increases, the bonding strength of the metallic bond is enhanced and the plasticity and toughness of system are improved. In addition, the 3d-orbitals of both atoms are mainly involved in bonding, which is the key reason for the improvement of plasticity and toughness. Meanwhile, there are also some electrons gathered around the two atoms and have directivity, which indicates that there is also covalent bonding within the system. The existence of covalent bonds is the key to enhancing the mechanical stability of the system.