Polyaromatic hydrocarbons were separated by a capillary supercritical fluid chromatographic (SFC) column and detected by a UV detector at the wavelength of 280 $mu$m. The temperature-controlled restrictor was designed for UV detection. The temperature-controlled restrictor is a 20 cm length of deactivated fused silica of 7 mm i.d. which is held right after UV detector of the capillary SFC. The temperature of the restrictor will control the flow rate of the supercritical carbon dioxide mobile phase through the capillary column in SFC. Thus as the pressure in the column is increased from 1500 psi to 4000 psi during a pressure program, the temperature of 7 $mu$m fused-silica tube can be varied from 100 to 350 ${^{circ}C}$ to maintain a constant flow rate.