Abstract: Abstract: Biological ultraweak photon emission is divided into spontaneous photon emission and delayed photon emission. It is very important life information from living cells. The study of the ultraweak photon emission about germinating crop seeds is possible to provide a new method of sensitive, fast and nondestructive evaluation of the cell metabolism and functional status. The analysis technology of biological ultraweak photon emission plays an important role in many aspects such as the germination mechanism of seeds, the evaluation of salt tolerance and the identification of crop germplasm. In order to reveal the biological significance of the ultraweak photon emission from germinating corn seeds under salt stress, some corn seeds were placed in different concentrations of NaCl solution, and the changes of ultraweak photon emission in germinating corn seeds under the NaCl stress of different concentrations were studied in this paper. The results showed that the seed fresh quality and spontaneous photon emission from germinating corns in control group were gradually growing in the process of corn seed germination, and there was a positive correlation between the changes of seed quality fresh and spontaneous photon emission (correlation coefficient was 0.9614); the changes of spontaneous photon emission and fresh quality of germinating corn seed also showed a positive correlation under the NaCl stress of 50, 100 and 150 mmol/L (correlation coefficients were 0.9582, 0.9406 and 0.9389 respectively). The study also showed that NaCl stress inhibited the growth of the seed fresh quality and the increase of spontaneous photon emission in corn seeds during germination, and the higher the concentration of NaCl, the stronger the inhibition. The change of the spontaneous photon emission provides the information about the decrease of respiration metabolism and DNA synthesis in germinating corn under the stress of NaCl according to the biological significance of spontaneous photon emission. The study also showed that the delayed photon emission of germinating corn excited by blue LED had changed under NaCl stress, and in the control group, the kinetic parameters such as initial photon number and coherence time about delayed photon emission of germinating corn gradually increased with the germination time, and the integral strength of delayed photon emission of corn seeds increased rapidly in 2 days after absorption, then held steady. It was also found that NaCl stress inhibited the increase of the initial photon number and coherence time about delayed photon emission of germinating corn, and caused the integral strength of delayed photon emission from germinating corn seeds to decrease, the greater the concentration of NaCl, the smaller the integral strength of delayed photon emission. The changes of the kinetic parameters of delayed photon emission about germinating corn seeds showed that NaCl stress could cause reactive molecules in seeds cells to reduce, organization and metabolic order to become disordered, and cell function to decrease. These research results provide a reference for explaining the response mechanism about the germination of corn under salt stress.