In a one-dimensional radiation transfer model, energy distribution and spectral absorption mechanism of greenhouse effect under Pre-Industrial and current atmospheric compositions were analyzed. Coupling mechanism between greenhouse effect and surface temperature was investigated on the basis of greenhouse gas concentrations at current level. It shows that warm environment before Industrial Revolution is mainly due to three strong absorption bands of greenhouse gases, which are (100-370)cm^-1, (640-710)cm^-1 and (1370-2000)cm^-1 respectively. However, current global warming is originated from weak absorption bands of greenhouse gases, that is, radiation absorptions by (370-640)cm^-1 and (710-1370)cm^-1. Contributions to greenhouse effect increment of these weak bands after Industrial Revolution are 25% and 55% respectively. With rising temperature, contribution of right side of the earth's radiation peak wavenumber to total greenhouse effect shows positive change, while contribution of left side shows negative change.