Applications of neutron scattering in the study of structures and functions of biological macromolecules are reviewed. Low energy neutrons can induce elastic

quasielastic and inelastic scatterings in biological samples. By measuring the scattered neutron intensity versus momenta and energy transfers

the structure and dynamical information of the biological macromolecules can be obtained. From the scattering intensity function

form factor and structure factor

we can get information about the geometric size

shape

volume

mass

radius of gyration

distance distribution functions and concentration of the interest atoms especially hydrogen atoms

in the biological macromolecules. Moreover

compared with the X-ray method

neutron scattering causes less damage to biological samples.