The study is aimed at developing highly sensitive methods of laser analytical spectroscopy. The physical mechanisms of forming useful signals (selective ionization signal and cavity ring-down signal) were identified that provided registration of parameters of atomic and aerosol systems in the intensive pulsed laser field. High-sensitive laser methods of laser resonance ionization spectroscopy in vacuum, laser-enhanced ionization spectrometry in flame, and cavity ringdown laser absorption spectroscopy (CRLAS) are used for the determination of ultra-small concentrations of atoms in different phase states of the substance. Samples of aqueous standard solutions and solid metals of s (Li, K, Na, Ca, Cs), p (Al, In), d (Cr, Mn, Fe, Co, Ni, Cu, Ag, Au, Pt, Zn, Hg), f (Yb) elements, aluminum alloys, especially pure solvents, crystals (NH4F, NaF), semi-conductor materials (GaAs, Si) and various aerosols of salts (NaCl, CsCl, NaI, NaF, KCl AgNO3), chemicals, organic dyes, alloys, soils and rocks were studied. The new mechanisms of getting free particles are revealed and new methods increasing the efficiency of atomization, selective ionization and excitation of atoms in systems «flame», «rod – flame», in atomizer «graphite – furnace» are proposed. The particle size distribution of aerosols formed under the impact of high-power laser radiation on the surface of a solid sample has been studied. The dependence of the absolute concentration of aerosol particles on their size has been determined. Aerosol extinction coefficients and extinction efficiency have been measured using intracavity laser spectroscopy. For the first time new parameters of aerosols are revealed by physical and chemical properties of aerosol plumes from solid surfaces and aerosols of salt of metals and organic aerosols. Methods of additives and calibration curve were used to examine the effects of the matrix on the analytical signal of the studied atoms.