According to energy balance consideration, the ablation ratio formula of target irradiated by pulsed laser is derived, and the spatial-characteristic equations of plasma generated by pulsed laser are obtained by using fluid dynamic theory. Combining the ablation ratio formula with the spatial-characteristic equations of plasma, the effects of different laser power density and wavelength on the deposition characteristics of Kta0.65Nb0.35O3(KTN) thin film are studied on the basis of our experiments. And many valuable results are obtained which have been discussed in detail. The calculated results are in agreement with experiments on the whole.