In this paper,the bursting of rotating disc of cast iron is discussed by the snapshot when the disc burst,and ascertained the following facts:-1.At first the disc burst on a diametral section under centrifugal force,then it breaks into some pieces under bending.2.On account of Coriolis’force,the break of the disc under bending is not a symmetry as to the diametral section where the disc burst at first,as shown in Fig3, Fig.8(a)and(b).3.However,the influence of Coriolis’force can be neglected as long as the ratio γ1 of inner to outer diameter of the disc is comparatively small,and the break of the disc becomes about a symmetry as shown in Fig.8(c)and(d).