Accelerator-based neutron sources have been considered to be practical for boron neutron capture therapy (BNCT). Based on experience with the parameters of the Brookhaven National Laboratory BMRR reactor neutron source, which has been used in treatment experiments, the future accelerator-based neutron source for BNCT should have the properties of low energy distribution keV) and high flux (about neutrons per second per square centimeter) in the patient zone. Using protons to bombard thick targets, generating neutrons via the reaction, is one of the optimal choices for this kind of neutron source. Neutron yield data versus incident energy are necessary in order to select the proper incident energy and for estimating how high the incident proton current should be. The required proton beam current intensity is one of the key parameters for an accelerator useful for BNCT. In the present work, neutron yields of the reaction with a thick lithium target and incident energies of 1.885 and 1.9 MeV were measured at 0° with respect to the incident beam direction. The results are and neutrons/C sr, respectively. Neutron yield angular distribution measurements at 2 MeV incident energy were also performed. The proton beams were generated by the Peking University 4.5 MV electrostatic accelerator. The emitted neutrons from these reactions have the advantages of low energy distribution and forward angular distribution, which are requirements for a BNCT neutron source. The data obtained in this work can be used as a reference to study the accelerator-based neutron sources for BNCT.