This report describes the principle, method and characteristic of qualitative and quantitative nondestructive detection of defects in metal-cased linear explosive charge,and a comparison between x-ray and neutron photography is made as well. Some microdefects were deliberately made in the linear explosive charge cased in a silver tube with OD 7mm and ID 6mm to simulate the nondestructive detection of mild detonating fuse(MDF) and work out a detection procedure which can be used to examine the dot defects in MDF of OD 2mm with distinguish ability of 0.1mm.But the application of neutron photography is limited because the neutron source is very expensive except neuclear reactors.