The auther endeavoured to prove through experiments that estimation of the resonant frequencies of a circular saw blade system could be made by using the formulae for calculating the natural frequencies of an annular plate on condition that some dimensions were properly modified. It was found that the use of larger collars could not only reduce the mechanical noise from the saw blade but also improve the stability of the latter.Based on the results of idling tests of a circular saw blade, the auther considered that the aerodynamic noise source of a circular saw blade mainly originated from certain combination of monopole and dipole, and that the speed of a saw blade was the most significant factor which effected the level of noise from the saw blade. The influence of shape and dimensions of teeth on the level of noise from the saw blade was also discussed. Finally, in the paper some effective ways were introduced to reduce noise from a circular saw blade.