A method for detecting steel sample components by using a laser induced plasma spectral analysis device, wherein the spectral analysis device comprises a laser device, a laser import system, a spectrum export and collecting system, a spectroscopic system, and a spectrum receiving system; wherein the spectrum export and collecting system comprises a spectrum export subsystem and a spectrum collecting subsystem, the laser and the spectrum receiving system are controlled by instructions sent by a same pulse generator; wherein the laser device is an all-solid-state regeneration amplifier picosecond laser; the method comprises the following steps: 1) output of a nanosecond laser pulse realized by the laser device in a Q-switching manner, so that the output nanosecond laser pulse is focused on the sample by means of the laser import system, and plasmas are formed on the surface of the sample; 2) output of a picosecond laser pulse realized by the laser device by means of a regeneration amplification technology, so that the output picosecond laser pulse is also focused on the sample by means of the laser import system to enhance the spectral line emission from the plasmas formed by irradiation of the nanosecond laser pulse, to generate laser induced spectrums with enhanced spectral lines; 3) the fluorescence from the generated induced spectrums is exported to the spectrum collecting subsystem by means of the spectrum export subsystem; and 4) the collected spectrums are calculated, processed, and analyzed, so as to perform qualitative and quantitative testing of elements contained in the sample; wherein the regeneration amplification technology comprises that light beams of a picosecond seed source of the laser device are injected into a regeneration amplifier by means of a magneto-optic isolator; laser beams move back and forth in the regeneration amplifier; single-pulse energy is gradually amplified to a maximum value, and then emitted out of the regeneration amplifier by means of the magneto-optic isolator to implement output of a laser with a picosecond pulse width; and wherein the Q-switching manner comprises that seed light is blocked by means of a mechanical shutter, and meanwhile, an optoelectronic switch is made to work in a Q-switching mode, and output of a laser with a nanosecond pulse width is implemented in a Q-switching manner. 1) output of a nanosecond laser pulse realized by the laser device in a Q-switching manner, so that the output nanosecond laser pulse is focused on the sample by means of the laser import system, and plasmas are formed on the surface of the sample; 2) output of a picosecond laser pulse realized by the laser device by means of a regeneration amplification technology, so that the output picosecond laser pulse is also focused on the sample by means of the laser import system to enhance the spectral line emission from the plasmas formed by irradiation of the nanosecond laser pulse, to generate laser induced spectrums with enhanced spectral lines; 3) the fluorescence from the generated induced spectrums is exported to the spectrum collecting subsystem by means of the spectrum export subsystem; and 4) the collected spectrums are calculated, processed, and analyzed, so as to perform qualitative and quantitative testing of elements contained in the sample; wherein the regeneration amplification technology comprises that light beams of a picosecond seed source of the laser device are injected into a regeneration amplifier by means of a magneto-optic isolator; laser beams move back and forth in the regeneration amplifier; single-pulse energy is gradually amplified to a maximum value, and then emitted out of the regeneration amplifier by means of the magneto-optic isolator to implement output of a laser with a picosecond pulse width; and wherein the Q-switching manner comprises that seed light is blocked by means of a mechanical shutter, and meanwhile, an optoelectronic switch is made to work in a Q-switching mode, and output of a laser with a nanosecond pulse width is implemented in a Q-switching manner. wherein the regeneration amplification technology comprises that light beams of a picosecond seed source of the laser device are injected into a regeneration amplifier by means of a magneto-optic isolator; laser beams move back and forth in the regeneration amplifier; single-pulse energy is gradually amplified to a maximum value, and then emitted out of the regeneration amplifier by means of the magneto-optic isolator to implement output of a laser with a picosecond pulse width; and wherein the Q-switching manner comprises that seed light is blocked by means of a mechanical shutter, and meanwhile, an optoelectronic switch is made to work in a Q-switching mode, and output of a laser with a nanosecond pulse width is implemented in a Q-switching manner.