The oak longhorn beetle, Massicus raddei (Blessig) (Coleoptera: Cerambycidae), is a severe wood borer for forests of Quercus liaotungensis and Q. mongolicus in northeastern China. It needed three years to complete a generation with its life history uniformly. It was interesting that the developing stage of the longhorn beetle was about the same in Liaoning, Jilin provinces and Inner Mongolia, and thus its adult emergence period was all in the same year every three years. For the control of this pest we invented a black light trap to attract and kill its adults based on their biological characteristics of phototropism. In 2008, 24.16 ton of the longhorn beetle adults were killed by the special black light trap in Jilin Province with 430 individual adults per kg. averagely. According to the numbers (used as weight (kg.)) of the longhorn beetle adults attracted per night by the special black light from July to August in 2008, the relationship between the adult emergence period and temperature and humidity were analyzed. It was indicated that the emergence peak was from last ten days of July to first ten days of August; the adult emergence showed positive correlation obviously with temperature but negative correlation with relative humidity in the forest stands then. The relationship between the quantity of the longhorn beetle emergence and temperature and relative humidity was fitted preliminarily. The research results provide basal data for predetermining and forecasting the longhorn beetle adult emergence starting and lasting time, as well as for control techniques carrying on.