The Toluene sensor was installed in our designed 36 ml Teflon chamber. The desired vapor toluene was Toluene in the Erlenmeyer flask via adjusting two mass flow controllers. First, carried into the test chamber for 3 min to stabilize the sensor before Toluene sensing. Next The Toluene vapor generated from the bubbling system was introduced into the sensor chamber by switching valves #1 and #2. The resistance of Carbon Nanotubes sensor was measured by a simple voltage divider circuit with a constant applied voltage of 10 V. The data were recorded every second via our LabVIEW program with a NI USB DAQ 6008.