Deuterium–tritium neutron yield has reached up to about 1013 at the 100 kJ-level laser facility, which makes measurement of neutron emission images possible with the neutron imaging system. There are two methods to collect neutron images from the scintillator array, optical fiber taper and the lens system. Here, we report a design of the lens system for the neutron imaging system at the 100 kJ-level laser facility. The lens system, which consists of a nine-element collecting lens, with a spatial resolution of 20 µm and a light-collection efficiency of 5.9% has been designed.