Abstract: Synthesis Z=119, 120 superheavy nuclei is the goal that nuclear physics laboratories are chasing. Theoretically, it is helpful to design experiments and detect newly synthesized superheavy nuclei by giving reliable information such as projectile-target combination, incident energy, etc. Based on dinuclear system model, we explore the reaction mechanism affecting the generation cross section of the heavy ion nuclear reaction and calculate ^50\rmTi+^249\rmBk, ^50\rmTi+^249\rmCf projectile-target combination. Among them, we predicted that ^50\rmTi+^249\rmBk generation cross section is 0.021 1 pb. Considering the fusion process and survival process, we focus on the isotopic dependence of the projectile isotopes, such as ^52-59\rmCr+^243\rmAm, ^54-62\rmMn+^243\rmAm, ^56-72\rmNi+^238\rmU. It is shown that the fusion probability is significantly dependent on the projectile nuclear mass number, which directly affects evaporation residual cross section.