In order to extend the application range of linear ion trap spectrometer in aerospace field, the ion ejection efficiency of Triangular-electric linear ion trap (TeLIT) is improved by simulation studies in the research. Asymmetric radio frequency (RF) is applied on the electrodes to investigate the ion directional ejection by simulation software SIMION and AXSIM, and the influence of higher fields on ion directional ejection efficiency is studied by changing the angles of triangular electrodes. It's turned out that, when α is adopted the optimal parameter reported of 140°, the ion directional ejection efficiency could reach 89.5% with asymmetric RF voltage ratio of 20%. When α=135°, the ion directional ejection efficiency could be up to 95%,which is higher than the ejection efficiency of TeLIT with α=140°.What's more, the highest ion ejection efficiency with different α is investigated and the mass resolution of each mass spectrum is calculated. It shows that a mass resolution of 2 500 could be obtained with α=135° when the scan rate is 1 500Th/s.