Using TCT-GC/MS technique, diurnal emission cycles of volatile organic compounds (VOCs) from Pinus massoniana and Pinus elliottii were analyzed respectively. Results showed that terpenes, especially monoterpenes were the dominant components released from P. massoniana. Nearly eighty percent of the total VOCs were consisted of α- and β-pinenes, but the oxygenated VOCs was less abundant. Releasing peak of most VOCs was around 10:30am but a few VOCs at 1:30am . The lowest releasing points of VOCs were at 1:30pm and 10:30pm, respectively. Volatile components detected from P. elliottii were similar to those from P. massoniana. Releasing peaks of most VOCs from P. elliottii lasted from 12:00pm to 3:00pm while the others were at 6:00am. The peaking time of α-Pinene’s was around 3:00am when the other VOCs were at their lowest releasing point. The emission rates of VOCs were also influenced by environmental factors. The emission rates of VOCs increased corresponding to the temperature rising and the decline of humidity.