为了改善激光诱导击穿光谱质量，使用具有时间分辨功能的光谱仪采集激光诱导钢靶等离子体光谱，研究了钢靶等离子体辐射光谱随延迟时间的变化特性。结果表明，光谱强度和背景强度随延时皆呈指数衰减，原子谱线强度在前4 μs内衰减更快但寿命较长，离子谱线存在寿命较短；采集延时对不同谱线的信噪比影响不同，Mn I 403.08 nm、Cr I 428.97 nm、Cr Ⅱ 458.82 nm、Fe I 430.79 nm和Fe Ⅱ 503.57 nm谱线得到的最佳延时分别为8,2,0,2,4 μs。采用双线法和Boltzmann曲线法计算等离子体温度、Saha-Boltzmann方程计算电子密度，验证了在0～10 μs范围内采集到的光谱信号满足局部热平衡状态。

In order to improve the quality of laser induced breakdown spectroscopy, we used a time-resolved spectrometer to collect steel target plasma emission spectra. The relationship between the intensity of spectral lines and the delay time was discussed. It demonstrates that both the spectral intensity and background intensity decay exponentially with the delay time. Spectral intensity of atoms decreases faster in the first 4 μs but the atoms′ spectral lines exist for a longer time. However, ions′ spectral lines exist for shorter. Acquisition delay has different influence on signal to noise ratios of different spectral lines. The best delays of Mn I 403.08 nm ,Cr I 428.97 nm, Cr Ⅱ 458.82 nm, Fe I 430.79 nm and Fe Ⅱ 503.57 nm spectra obtained are 8, 2, 0, 2, 4 μs, respectively. The double lines method and the Boltzmann plot method were used to calculate the plasma temperature， and the Saha-Boltzmann equation was used to calculate the electron density. It is verified that the spectral signal meets the local thermal equilibrium state in the acquisition time range of 0-10 μs.