Transformation of DNA into microbial cells via heat-shock approach has been well established in the field of molecular biology for decades. Herein we described an unexpected finding that heat-shock may not play an essential role in the transformation process. This observation was verified via UV-Vis and fluorescence spectroscopies, and confocal microscopy images for various DNAs and bacterial cells. The non-heat-shock approach proposed in this study can be a convenient and beneficial modification for DNA transformation, especially for those laboratories lacking ice machine and heat-shock equipment.