The computation theory of tidal strain and tidal stress in the Earthls interior was introduced in detail. Based on the PREM Earth model, the Love numbers in the Earth% interior were computed. Consequently, the time series of the six independent components of tidal strain and tidal stress at different depths and different latitudes were constructed, respectively. The numerical results show that the magnitude of the tidal stress is of the order of 103 Pa while the magnitude of the tidal strain is of the order of 10-8. The magnitudes of both tidal stress and tidal strain vary heavily with respect to the depth. Similarly, the six independent components of the tidal stress or the tidal strain are highly dependent on the latitude. But there is no strict north- south symmetric change of magnitude with respect to latitude. However the relation between magnitude and latitude can be derived from the geodetic coefficients of spherical harmonic expansion of tide generating potential. The results in this study are effectively applicable in tidal correction on tidal strain or tidal stress observations in the Earthrs interior. On the other hand, the results were applied in the problem of tidal triggering of earthquake in central China area. The statistic results imply high correlations between occurrence times of earthquakes and the tidal normal stresses on fault planes as well as the first invariant of tidal stress tensor. On the contrary, the correlations do not appear in other stress components such as tidal shear stress and tidal Coulumb failure stress.