  We investigate the two loop electroweak corrections to B meson rare decays
$\bar B\rightarrow X_s\gamma$ and $B_s^0\rightarrow \mu^+\mu^-$ in the minimal
supersymmetry standard model (MSSM) extension with two triplets and one singlet
(TNMSSM). The new particle contents and interactions in the TNMSSM can affect
the theoretical predictions of the branching ratios ${\rm Br}(\bar B\rightarrow
X_s\gamma)$ and ${\rm Br}(B_s^0\rightarrow \mu^+\mu^-)$, and the corrections
from two loop diagrams to the process $\bar B\rightarrow X_s\gamma$ can reach
around $4\%$. Considering the latest experimental measurements, the numerical
results of ${\rm Br}(\bar B\rightarrow X_s\gamma)$ and ${\rm
Br}(B_s^0\rightarrow \mu^+\mu^-)$ in the TNMSSM are presented and analyzed. It
is found that the results in the TNMSSM can fit the updated experimental data
well and the new parameters $T_{\lambda},\;\kappa,\;\lambda$ affect the
theoretical predictions of ${\rm Br}(\bar B\rightarrow X_s\gamma)$ and ${\rm
Br}(B_s^0\rightarrow \mu^+\mu^-)$ obviously.
