13 normal maize inbred lines with quite different quantitative traits were used as experimental materials in this paper. The results showed that there was significantly positive correlation between genetic distance and plot yield, mid-parent heterosis, super heterosis, or SCA of yield. In a certain range, the longer the genetic distance between parental inbred lines, the stronger the heterosis. Therefore, in genetic practice, it was necessary to take the molecular genetic distance between inbred lines as an important reference.