Abstract: In recent years, under the influence of the high temperature, some maize varieties showed a serious phenomenon of no seed. In this experiment, we took two new varieties ‘Xundan 518’ and ‘Yongyou 618’ as our main materials, and we mainly studied the silk vigor in the current climate. By choosing silks of different day ages for artificial pollination, we took statistics on the ear length, the ear diameter, barren tip, 100 grain weight, spike grain number and spike grain weight after the harvest. With the increasing of the silk age, spike grain number and spike grain weight showed an upward trend at first, peaked from the second to fourth day, then declined slowly; the ear diameter and 100 grain weight showed a downward trend; all the silks put forth within two days. After the correlation coefficient analysis among all the traits, we found that the spike grain number had a maximal relationship with the spike grain weight. Because of the long duration of silk vigor and high yield under high temperature, ‘Xundan 518’ and ‘Yongyou 618’ are the new heat-tolerance varieties