The Shanghai laser electron gamma source (SLEGS) is a powerful tool for exploring photonuclear physics, such as giant dipole resonance (GDR) and pygmy dipole resonance, which are the main mechanisms of collective nuclear motion. The goal of the SLEGS neutron time-of-flight (TOF) spectrometer is to measure GDR and specific nuclear structures in the energy region above the neutron threshold. The SLEGS TOF spectrometer was designed to hold 20 sets of EJ301 and $${\hbox {LaBr}_{3}}$$ LaBr 3 detectors. Geant4 was used to simulate the efficiency of each detector and the entire spectrometer, which provides a reference for the selection of detectors and layout of the SLEGS TOF spectrometer. Under the events of $$^{208}\hbox {Pb}$$ 208 Pb , implementations of coincidence and time-of-flight technology for complex experiments are available; thus, $$\gamma $$ γ and neutron decay events can be separated. The performance of SLEGS TOF spectrometer was systematically evaluated using offline experiments, in which the time resolution reached approximately 0.9 ns.