Abstract: In this research, alpha imaging in SQS (Self Quenching(Self-Quenching Streamer) mode is investigated using a triple Thick Gas Electron Multiplier (THGEM) detector by Monte Carlo method and experimental data. At firstFirstly, a semi-empirical equation is obtained that represents the relation between the SQS voltage and the alpha energy in every hole of the triple THGEM. Accuracy of this equation is tested and confirmed bywith a high degree of consistency. Secondly, the images of objects that are irradiated by an Am-241 alpha source (5.49 MeV) are recorded by a CMOS camera using a triple THGEM detector in SQS mode. The resolution of images in this paper is a function of the exposure time. For an alpha source with 150 kBq activity, an optimal time interval for exposure is about 30 seconds. For exposure time less or more than 30 sseconds, the images are incomplete and ambiguous respectively. The overall objective of this work is to facilitate the alpha radiography in nuclear imaging through a triple THGEM without any amplifier or complicated electrical equipment.