Nearfield holography (NAH) measurement usually needs discrete Fourier transform (DFT) for spectrum analysis. When the signal is sampled in a nonsynchronous manner, the DFT spectrum analysis will yield leakage errors, which will reduce the reconstruction precision. A method based on nonprior base analysis is adopted. The base vectors are determined through searching the maximum peak value of the inner product. The covering effect of strong signals can be decreased, and the result is more accurate. This method is introduced to the NAH measurement to analyze the complex sound pressure on the holography surface. After that, the radiation sound field of point source is reconstructed. The result shows that the accuracy of sound field reconstruction is improved.