Native luminescent defects were investigated in AlN nanopowder (NP) using spectral characterization methods. Photoluminescence and its excitation spectra were studied within a wide temperature range from 8K up to room temperature. It was found that in AlN NP a broad luminescence band appears within a blue spectral region consisting of at least two sub-bands at 415 nm and 390 nm, which can be related to presence of two different but in the same time similar defect types. These luminescent defects are located either inside the bulk material or on the material surface. Interaction of the surface defects with environmental oxygen was found resulting in quenching of the blue luminescence (BL). Three BL mechanisms were revealed, depending on spectral region of the exciting light, resulting in intra-center luminescence, recombination luminescence and exciton caused luminescence. Variations of the F-centers are proposed to be responsible for the BL in AlN NP. Display omitted •In AlN blue luminescence appears caused by intra-center or recombination processes.•The blue luminescence in AlN is related to nitrogen vacancy-based F-centers.•Luminescent F-centers are located either in the bulk of AlN or on its surface.•Oxygen is interacting with F-centers from AlN surface reducing its luminescence.•In AlN nanopowder the blue luminescence from the surface defects is dominant.