LAMOST regular survey has successfully observed more than 100, 000 galaxy spectra, which provides important data for mining the precious and rare objects to improve the existing theories. In this paper, the spectrum J140242.45+092049.8 is particularly chosen from LAMOST DR3 by using the outlier mining method based on the relevant subspaceand intensively discussed these rare characteristics respectively. First of all, the dual-redshift system (absorption system: z1=0.020 95, emission system: z2=0.069 5) are measured and identified by fuzzilyrecognizing the characteristics lines and cross matching the information of the homologous spectrum observed with SDSS. As a whole, the Δz=0.048, which is far greater than the physical interacting threshold (Δz<0.008) provided with Keel, indicating that they are superimposed in the light of sight rather than physical interacting occurring between the foreground galaxy and background one, and the possibility of lens for such “absorption+emission” mode dual-redshift spectrum is illuminated by studying the availableliterature and analyzing the image feature provided with SDSS. For the foreground galaxy (absorption system), the strong Balmer absorption lines and iron lines appeared simultaneouslyin the spectrumimplies that this object will be most likely be E+A galaxy. For the background galaxy (emission system), the characteristic of double peak emission lines is analyzed and the strange relationship between the emission lines is also discussed in the end.