Abstract: In this paper, the calculated results of elements Z\leqslant118 based on the dinuclear system model and other models are compared with the experimental data. It is proved that different models are reliable in predicting the production cross sections of superheavy nuclei. The prediction results of superheavy nuclei Z=119 and Z=120 by different models are compared and analyzed. It is found that the optimal projectile-target combinations to synthesize superheavy nuclei Z=119 and Z=120 are ^48\rmCa+ ^\rm252\rmEs and ^40\rmCa+^\rm257\rmFm, respectively, and it is likely that the new isotopes Z=119 will be synthesized in the experiment before the new isotopes Z=120. Because of the lack of target with Z>100 in the laboratory, attempts are being made to find heavier projectiles than ⁴⁸Ca to synthesize superheavy nuclei Z=121 and Z=122. The superheavy nuclei Z=121 can be synthesized by reactions V+Cf. However, the production cross sections of superheavy nuclei Z=122 are very small, which requires us to improve the detection and identification techniques in the future. We hope that the discussion in this paper can provide some guidances for experimental and theoretical nuclear physicists in the future.