Double disk chopper is widely used in neutron scattering spectrometers
its main function is to cut the se-quential neutrons into neutron pulses.Aiming at a time of flight neutron reflectometer under construction
we intro-duce the design of double disk chopper in detail.The resolution is optimized through theoretical calculation
and the neutron flux after the chopper is estimated using the McStas codes.The results can be a reference for double disk chopper design and production.