Magnetic properties of FeCoMoB glass-coated microwires with high positive magnetostriction have been investigated during the process of devitrification in the temperature range: 0-600 °C by ferromagnetic resonance (FMR) studies. The FeCoMoB microwire shows natural ferromagnetic resonance that reflects a complex anisotropy distribution. FMR spectrum for as cast sample shows up to four resonance maxima when ranging frequency from 10 MHz up to 11.3 GHz. After annealing, the anisotropy distribution becomes more regular and the number of FMR peaks decreases. The anisotropy and stress amplitude has been estimated from the FMR spectra, showing a strong decrease with annealing temperature and being low and constant for the nanocrystalline state. In addition, Gilbert damping decreases with annealing temperature, too. The low Gilbert damping (∼0.01) for the nanocrystalline state makes the nanocrystalline FeCoMoB microwire an ideal material for applications in which fast magnetization processes are required.