In this paper, a Lacuna phenomenon over Wuchang, China is revealed and studied. The obvious difference between this Lacuna phenomenon and the common one is that it occurs on a geomagnetieally quiet day.Some other very rare phenomena occurring in that day are also studied. It may by a coincidence that several rare phenomena come together on the same day. But at least it enlightens us on that the special events are liable to recognization on geomagnetieally quiet days.