Abstract: Double pulse laser-induced breakdown spectroscopy ( LIBS) technique for the determination of Cu in pig feed was studied in this paper.Combined with orthogonal design, parameters optimization of Cu in pig feed samples, LIBS test was carried out.According to the sum of the indexes in the visual analysis of the orthogonal experiment, the best experimental parameters were obtained.The laser energy of A was 157.77 m J and B was 196.87 m J.And the delay time of laser was 450 ns and gathering was 1.28 μs.Based on partial least squares ( PLS) , the influence of different points smoothing and various pretreatment methods to the PLS model prediction effect were compared.Finally, the combination of 9 point smoothing pretreatment could effectively reduce the noise signal.It could improve the accuracy of PLS model for analyzing LIBS spectral data.Model predictions were as follows: correlation coefficient ( r) , root mean square error of prediction ( RMSEP) and average relative error ( ARE) were0.9879, 15.10, 8.24%, respectively.