Abstract: Through the analysis of dark matter property, it is found that dark matter particles and three-dimensional isotropic globular galaxies constitute a spherical harmonic oscillator. According to the energy equation of the spherical harmonic oscillator, the classical orbit of a three−dimensional isotropic spherical harmonic oscillator is an ellipse. Different from the traditional star system that the center of the elliptical gravity is the focus of the ellipse, the center of the ellipse is the symmetry center. The dark matter particles must satisfy the condition E≥0, which is different from the traditional condition E≤0 of the elliptical. orbit.