Tokamak is considered as the most promising experimental setup for achieving controllable nuclear fusion requirements. The parameter \beta_\rmN is an important parameter for tokamak devices: high \beta_\rmN benefits not only to plasma fusion but also to the enhancement of fusion reaction efficiency and the facilitation of steady-state operation. The HL-2A tokamak device has achieved stable plasma with \beta_\rmN exceeding than 2.5 through neutral beam injection heating, and transiently reached \beta_\rmN = 3.05, with a normalized density (n_\rme,l/n_\rme,G) of about 0.6, stored energy (W_\rmE) of around 46 kJ, and confinement improvement factor (H_98) of about 1.65. In this work, the integrated simulation platform OMFIT is used to analyze the plasma at \beta_\rmN = 2.83 and \beta_\rmN = 3.05, and the obtained W_ \rmE, n_\rme,l/n_\rme,G, H_98, \beta_\rmN, etc. are consistent with the experimental parameters. The bootstrap current (f_\rmBS) can reach to 45\text% and 46\text%. At both of the above moments, there are ion temperature double transport barrier (DTB) generated by the coexistence of internal transport barrier (ITB) and edge transport barrier (ETB), while high \beta_\rmN is usually related to DTB. In addition, the formation of ion temperature ITB in the HL-2A device is further analyzed, which is attributed to the dominance of turbulent transport in plasma transport, the suppression of turbulent transport in the core by fast ions and \boldsymbol E\times\boldsymbol B shear, and the resulting improvement in confinement, thereby ultimately leading to the formation of ion temperature ITB. The ITB of ion temperature and the ETB of H-mode synergistically contribute to the creation of high \beta_\rmN plasma.