Abstract: The present invention relates to a selective catalytic reduction denitrification equipment for efficiently removing visible emission (yellow plume; yellow fume) by using Selective Catalytic Reduction in order to remove the yellow fume during starting-up a gas turbine in a combined heat power or the like. To this end, a reductant supply condition is improved in an existing nitrogen oxide reduction apparatus, which uses a selective catalytic reduction method, and a ratio of NO2/NOx is precisely adjusted, thereby creating an excellent effect of removal of yellow fume from exhaust gas at a low temperature of 130° C. or lower.