In this paper, Newton's gravitational formula is modified by the principle of spatial energy field superposition, and the problem of "missing mass " of galaxies is analyzed by this modified gravitational formula. It is concluded that the velocity of stars in the galaxy is too fast because the energy field intensity of the inner space of the galaxy or space-time curvature of the galaxy is seriously underestimated, and there is no dark matter and supermassive black hole in the galaxy.