When using detectors with better efficiency but lower energy resolution such as NaI（Tl） for the thermal neutron capture prompt gamma-ray on-line analysis in a hostile environment

a method based on elemental standard spectra is more effective. The method includes acquisition of a standard spectra’s closure set

spectra fitting with the weighted-least square method

and calibration of the elemental relative sensitivity and the normalized parameters. With a NaI（Tl） detector and 252Cf neutron source

the NaCl solution was analyzed with a good precision.