Keywords: 
• superheavy element /
• langevin equation /
• cross section

Abstract: A possible way to synthesize superheavy element (Z=117) by using ⁴⁸Ca+²⁴⁹Bk reaction is studied with two step model. The fusion process is divided into two steps: the sticking process that the projectile approaches to the target to get contacted with the target by passing over the Coulomb barrier， and the formation process that the dinuclear system evolves from contact into compound nuclear state. Combined with the statistical evaporation model， the formation cross section of ²⁹⁷117 is calculated. The result shows that the residue for 3 neutron evaporation is 0.34 pb at excitation energy E*=31 MeV， which is detectable in laboratory.