The quantitative analysis accuracy and detection limit of laser induced breakdown spectroscopy (LIBS) under magnetic constraints is studied.In this paper,the magnetic field constraint is applied to LIBS technology.Ni II 221.648 nm is selected as the analysis line of Ni element,Fe II 258.588 nm is the internal standard spectrum line,the standard stainless steel sample of 303,304,316,321,347 is used to carry out the Ni element calibration curve in stainless steel combined with the internal standard method,and the 310 stainless steel sample is used for calibration curve accuracy analysis and detection limit analysis.The experimental results show that the magnetic field constraint can effectively enhance the spectral intensity of the plasma,the calibration coefficient of the calibration curve obtained by the internal standard method is higher,and the detection concentration of the 310 sample is more accurate than the LIBS technique.The detection limit of the Ni element is decreased by 1.7 times compared to traditional LIBS.