The absolute number density of nitrogen dioxide (NO2) seeded in argon is measured with cavity-enhanced laser-induced fl uorescence (CELIF) through using a pulsed laser beam for the first time. The cavity ring down (CRD) signal is acquired simultaneously and used for normalizing the LIF signal and determining the relationship between the mea-sured CELIF signal and the NO2 number density. The minimum detectable NO2 density down to (3.6±0.1)×108 cm?3 is measured in 60 s of acquisition time by the CELIF method. The minimum absorption coefficient is measured to be (2.0±0.1)×10?10 cm?1, corresponding to a noise equivalent absorption sensitivity of (2.2±0.1)×10?9 cm?1·Hz?1/2. The experimental system demonstrated here can be further improved in its sensitivity and used for environmental monitoring of outdoor NO2 pollution.