Relying upon the solution of the relativistic equation of a charged particle motion that was obtained by A.A. Rukhadze et al., the spectral and angular characteristics of ultra-relativistic intensive radiation of a relativistic charged particle have been studied, the particle being linearly accelerated by a superpower laser pulse. The case where the particle propagates in vacuum without brake light was examined. The interaction of the charged particle with the large-amplitude ultra-short laser pulse was analyzed in details using the relativistic consideration. Formulae for the average radiated power of the relativistic charged particle, depending on the initial conditions, the electromagnetic-wave amplitude, intensity and polarization were obtained. For the case where the laser pulse can be represented by a monochromatic plane wave, analytical expressions for the radiation characteristics were put forward and the phase-angular distributions of relativistic radiated power and intensity were found. The Fourier transform of the electric-intensity radiation field of the charged particle and the particle’s spectral density radiation in the field of a plane monochromatic wave for different types of polarization (linear and circular ones) were determined.