In light of Chen’s formulas of the fine-structure constant [2,3], we construct similar formulas to calculate proton and neutron to electron mass ratios, H, He and Li atoms to electron mass ratios and elementary particles to electron mass ratios. It was found that the formulas of elementary particles to electron mass ratios had two types, accordingly elementary particles were supposed to have two genders, i.e., Yang (convex) or Yin (concave), and the Yang/Yin ratio of all quarks and leptons is 1/2. Consequently, a hypothetical model called Mass Model of Elementary Particle was established. In the model, a formula of an elementary particle to electron mass ratio is consist of a Time Factor (TF) times a Space Factor (SF). A Time Factor is a single integer, a Space Factor has an integer plus or minus at least one modified sub-factor (called Sub-space Factor (SSF)), which decides the particle’s gender is Yang or Yin. Based on the model, all elementary particles (including neutrinos and the particle of dark matter) to electron mass ratios were calculated, the mystery why quarks and leptons have three generations could be explained, and the mystery of matter and antimatter imbalance in the universe could be explained.