Based on recent measurements of magnetic fields of the OBA stars we studied the statistical properties of their magnetic fields. As one of the statistically significant characteristics of the magnetic field we use the average effective magnetic field of the star ⟨B⟩. The distribution function f(⟨B⟩) of magnetic fields OBA stars is investigated. The function f(⟨B⟩) has a The function f() has a power-law dependence on the with an index of about 2-3 and a fast drop at ⟨B⟩ ≤ 300G for BA-stars and ⟨B⟩ ≤ 80G for O-stars.