Abstract: The symmetry of the in-group particles, which are of three generation fermions, and the “out-group”ones, which are not admitted by three generation fermions, was discussed. Itwas found that the“out-group”antiparticles of Bose type, which came into being because of CP ( charge conjugation-parity conservation) violation in the early universe and became heavier due to the phase transformation from low temperature to high temperature, are the supersymmetry companionsof the“in- group”particles of Fermi type. The mass of a neutralino, which is the lightest particle of the supersymmetry companions andmay be ofdarkmatter, was calculated to be about320 GeV. The ratio of the number density ofphotons to thatofprotons calculatedwith Planck distributionmethod is about 0. 6×1010, which is close to the observed value (about1010) available in literature. A photon has the quark-gluon structure according to an analysisof the relationship between itsmass and structure, which is consistentwith the experimental result reported in literature.