The sound localization methods are used for detection of noise source locations of prototypes of mechanical products including automobile engines. There are several types of sound localization methods. In middle frequency around 1kHz, which is most sensitive frequency for human auditory, these sound localization methods have enough resolution in their reconstructed images, and they are effective to localize the sound sources. For high frequency sound localization, the holographic type methods take long time in its measurement. To overcome this problem, I have developed a converted method of Nearfield Acoustic Holography (NAH) method, which is one of conventional holographic sound localization method. However, in low frequency, all holographic localization methods do not have enough resolution in reconstructed images.I am now developing new sound localization method, Double Nearfield Acoustic Holography (DNAH) method. This method is converted method of conventional NAH method. In this proposing method, the measurement configuration is changed, the measurement plane is doubled. And, the analyzing theory is changed to new theory. By using this method, the resolution of low frequency sound localization is improved.In this paper, the analyzing theory of proposing method is explained. And the results of numerical simulations to discuss resolution of new method will be explained.