Three methods used to determine luminance at tunnel portals were analyzed and compared. The three methods were look-up table method, environment diagram method and blackening method. But these methods didn't fully consider the regional environment of tunnel and luminous climate. In order to rapidly and accurately determine scenery luminance at tunnel portals, measurements were conducted in seven Congguan highway tunnels. Based on the onsite measurements, the relationship between scenery luminance at tunnel portals and horizontal illuminance were established. Statistical analysis on local light climate data were carried out to confirm standard value of luminance at tunnel portals L_S and the design reference value of typical scenery luminance at tunnel portals in Dongguan. And typical scenery luminance values of four towards in Dongguan area could be determined.