The form and internal structure of bombs recently erupted from the Laoh ei shan and Huos haoshan volcanoes in Wudalianchi, China, is systematically summarized and studie d. By estimating the volumes of spheroidal, fusiform, elliptic, almondshaped a nd cowdung bombs in different models, a more accurate expression of bomb volu m e is proposed. Furthermore, the dynamics of formation, ballistic trajectory and colliding deformation of bombs is tentatively studied and discussed. According t o the scale of the Laoheishan volcano and the distribution of bombs around it, t he range of height,at which bombs ascend, has been calculated.