Published in;Scientific Inquiry, 8(2): 256-262.;Science, 2007, (20): 6-8. (in simplified Chinese);Chinese Academic Forum, 2006, (34):55-57. (in traditional Chinese);This paper introduces the essences of mass, time, length and energy, as well as their standard measurement units, analyzes mass-velocity relationships in different theories, and comments on these relationships. Also the paper negates the mass-velocity equation and the mass-energy equation in the special relativity, analyzes the source and generating mechanism of atomic energy. The author deems that mass is mass, energy is energy, mass cannot be transformed into energy and energy cannot be transformed into mass. These two concepts can??t be converted into each other. There are mass conservation and energy conservation, individually.

Keywords: special relativity, mass, energy, velocity of light, mass-velocity equation, mass-energy equation