The Largest Scale We Can Detect in the Universe and the Inflation

From the damping of the Cosmic Microwave Background Radiation (CMB) anisotropy power spectrum at large scale and the recent accelerating expansion of the Universe, we find that, there may be a largest scale which we can detect in the Universe. From this, we can get the inflation parameters as spectrum index $n_s$, e-fold $N$, Hubble parameter $H$, the ratio of tensor and scalar $r$, the lasting time of reheating time $\alpha$ for special inflation models. We do them in three inflation models, and find that all the results fit very well with the observations and the inflation theory.