The invention belongs to the technical field of spacecraft structures, and relates to an allowance test assessment method for a detonation fuse separation device, and specifically relates to a test method for comprehensively assessing separating property allowance and structure dynamic strength margin of a mild detonation fuse separation device. The method uses a mild detonation fuse which contains 120% design explosive quantity to perform the structure dynamic strength margin test, so as to assess the anti-explosion impact property of residual structures of a protective cover and a separation ring under high explosive quantity, and ensure integrity of the structures. A test sample whose centering deviation is relatively large is used, and a mild detonation fuse in 67% design explosive quantity is used to perform a separating property allowance test, so as to assess low explosive quantity separation reliability in centering deviation. The method can fully verify the separating property allowance and structure dynamic strength margin of the mild detonation fuse separation device.