The purpose of this study was to evaluate the impact factors of temperature and relative humidity on formaldehyde emission from building materials. The study was conducted under the conditions of temperature $25^{circ}C$, $30^{circ}C$, $35^{circ}C$ and humidity 50% and 80% on formaldehyde emission from MDF(Medium Density Fiberboard), with PVC flooring and wallpaper. The test was carried out at 12 specimens which were in a different set of temperature and humidity by using small chamber system. Formaldehyde was sampled and analyzed by HPLC. The results of this study are as follows; Formaldehyde emission rate showed the dependence on temperature in the range of 2 $5^{circ}C{sim}35^{circ}C$ and a weak dependence on humidity in the range of 50%~80%. The enhancement effect of temperature and humidity on formaldehyde emission was related to the formaldehyde contents in the material.