The invention discloses a detonating speed measuring device and method of a detonating fuse. The device comprises the detonating fuse, a detonator, a metal tube, a pressure transmission medium, a data acquiring instrument and a plurality of pressure sensors, wherein the detonating fuse is used for detonating after igniting a detonating cap through the detonator; the metal tube comprises an inner metal tube and an outer metal tube; the plurality of pressure sensors are adhered at equal intervals on a main wire at the inner wall of the outer metal tube and are correspondingly connected with the data acquiring instrument; the inner metal tube passes through the outer metal tube and is fixed in the middle position; the detonating fuse passes through the inner metal tube and is fixed in the middle position; the pressure transmission medium is arranged in the inner metal tube. With the adoption of the device in the actual application, the problems that a probe of an ultrathin detonating fuse is difficultly fixed during speed measuring, the probe bound on the side of a thin detonating fuse is difficultly accurately and timely triggered, and the probe influences the detonating wave spreading of the detonating fuse, can be solved, thus the detonating speed measuring accuracy of the ultrathin detonating fuse can be improved, and as a result, the detonating speed of the ultrathin detonating fuse can be accurately measured.