On the basis of ref. [1], the time-resolved absorption spectrum of vibrational excited states v3 in BCl3 molecules are observed and investigated in higher laser energy flux. The excitation of vibrational states and a variety of energy transfer processes in relaxation, as well as their dependence on the pumping laser energy, the pressure of BCl3 and other parameters are measured. The result shows that there exists an ensemble of nonthermal distribution in vibrational states and the rotational energy transfer plays an important role in generating this nonthermal distribution. The processes of development of the BCl3 vi-bratioal excited absorption spectrum are discussed by using a simplified dynamical collision model. A simple relation Prv-v= c/K′(Tv,T<0,q) for the redistribution of the vibrational states and the analytical expressions for the equivalent vibrational temperature and the average number of the absorbed photons are obtained. They are qualitatively in agreement with experimental results.