The bamboo charcoal adsorption, combined with photocatalytic pre-treatment, was utilized to remove low-concentration nitrogen oxides (NOx) from the cultural relics conservation micro-environment used to conserve and protect cultural relics. The efficiency of NOx removal under different conditions was studied with various lamp source and levels of relative humidity. These studies indicated that there are no distinct difference between UV illumination and solar light illumination. The optimal sequence for air purification is photocatalysis followed by bamboo charcoal, type 4A molecular sieve, and bamboo charcoal absorption. The outlet concentration of NO and NO2 were 1.98 [mu]g/m3 and 1.80 [mu]g/m3 respectively. With an increase of relative humidity the NOx removal rate decreased; however, the combined purifier can work reliably for longer periods and keep outlet NOx concentrations below 4x10-9. In conclusion, bamboo charcoal adsorption, combined with photocatalytic has excellent performance and should be widely employed as a protective technology in the micro-environment conservation.