In recent years, the world’s shortage of ³He resources has led to the high cost of ³He neutron detectors. The boron-based neutron detectors using boron carbide films as neutron conversion layers have gradually become the most promising alternative. In this paper, we prepared Ti/B₄C multilayers using direct current magnetron sputtering method. The structure and composition of the films were characterized by transmission electron microscopy (TEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS). The results show that there is crystallization in the Ti layer. H, O, N are the main impurities in the films, and are mainly distributed in the Ti layer and B₄C-on-Ti transition layer. Higher base pressure can reduce the impurity content and increase the proportion of B content in the boron carbide films, thus improving the neutron conversion efficiency of the films. The results of neutron detection efficiency test prove that the high base pressure can effectively improve the efficiency of boron carbide neutron conversion layers.