A statistical method has been developed to process thin samples photon image. In studying of ultraweak luminescence ( e.g. the cell ultraweak bioluminescence ), it is need to apply a image intensifier to get visible photon counting image. The photon images are unavoidably influenced by intensifier dark noise and background noise, which make the signal photons submerged in noise photons. According to the statistical difference of signal photons and noise photons, a signal test and evaluation method is given to test whether the photons belong to the signal photons and get a concise criterion. By this criterion the noise photons can be distinguished from original image and be discarded to get S/N improved photon image. Using this method a human palm ultraweak luminescence photon image is processed.