In the experiment of this work, high purity hafnium (Hf) sample are irradiated with the a 1.064 μm Nd∶YAG pulse laser to generate plasmas in a vacuum chamber, and the soft X ray time integral spectra of Hf plasma in the wavelength range of 1.0 ~ 8.5 nm under different power densities are measured. First, the atomic spectrum data of unresolved transition arrays (UTA) atomic spectrum data is calculated based on Cowan program, and the data are broadened to Gaussian line shape, which is in good agreement with the experimental spectra. Then, the ion abundances of Hf plasma from Nd∶YAG laser with electron temperature ranging from 0 to 500 eV are calculated based on the collision radiation balance model (CRM). The results show that the abundance of high valence Hf ions increases with the increase of electron temperature, which is consistent with the experimental spectral analysis. Comparing experimental and theoretical calculations, it is found that the indistinguishable transition arrays of 4f ⁿ-4f ⁿ-15g of Hf XXI-Hf XXV and 4d ⁿ-4d ⁿ-15p of Hf XXVII-Hf XXXV are located in the water window band. Finally, based on MED103, the spatiotemporal evolution of the plasma under the experimental conditions is simulated, and the temporal and spatial distributions of electron density and electron temperature are obtained. Through the analysis and comparison of electron temperature and electron density distribution under different laser power density, the experimental spectrum and CRM calculations results are further verified.