We consider the acceleration of electrons in vacuum by means of the circularly-polirized electromagnetic wave, propagating along a magnetic field. We show that the electron energy growth, when using ultra-short and ultra-intense laser pulses (1 ps, 1018 W/cm2, CO2 laser) in the presence of a magnetic field, may reach up to the value 2,1 GeV. The growth of the electron energy is shown to increase proportionally with the increase of the laser intensity and the initial energy of the electron. We find that for some direction of polarization of the wave, the acceleration of electrons does not depend on the initial phase of the electromagnetic wave. We estimate the laser intensity, necessary for the electron acceleration. In addition, we find the formation length of photon absorption by electrons, due to which one may choose the required region of the interaction of the electrons with the electromagnetic wave and magnetic field. We also show that as a result of acceleration of electrons in the vacuum by laser radiation in a magnetic field one may obtain electron beam with small energy spread of the order δε/ε ≤ 10−2.