Abstract: Due to the shortage of 3He gas and the rapidly increasing price, it is urgent to seek a new neutron detector to replace 3He gas detector. Scintillator based on 6LiF/ZnS(Ag) is an ideal material for thermal neutron detection because of its large neutron cross section, high detection efficiency and strong γ suppression. The neutron detector model was established using Monte Carlo procedure MCNP5 in this work. The neutron detection efficiency was calculated under different mass ratio and thickness parameters. The simulation results show that the thermal neutron detection efficiency improves with the increase of detector thickness. This means that one can use laminated construction to increase neutron efficiency in subsequent detector design. The simulation results also show that the thermal neutron detection efficiency improves with the increase of the mass ratio of 6LiF and ZnS(Ag) (the value increases from 1∶6 to 1∶2 in this work). 6LiF/ZnS(Ag) detectors in five different thicknesses (100, 200, 250, 300, 400 μm) and two mass ratios with 1∶3 and 1∶4 were manufactured. A 252Cf neutron source and a 60Co γ source were used to measure the performance of detectors. Detection efficiency measured results show that the detectors with mass ratio of 1∶3 and 1∶4 have higher detection efficiency of thermal neutrons. They both can reach 30% or more. However, the detector with mass ratio of 1∶3 is better than that of 1∶4. The detector with 400 μm thickness has higher thermal neutron detection efficiency. γ sensitivity measured results show that the detector has a strong ability to inhibit γ signal. In certain threshold voltage condition, the γ sensitivity can reach 1×10-7. There is no significant difference in γ sensitivity of detectors with two mass ratios of 1∶3 and 1∶4. To consider neutron detection efficiency and γ sensitivity comprehensively, the threshold voltage setting in 45 mV was appropriate under the current detector conditions. In general, the detector developed in this paper has a good property and it is equivalent to the international level of similar products.