Abstract: By means of CUSP model of catastrophe theory. this paper has studied thephysics process of rockburst occured on circular chamber. The present paper has nolonly described the instability process of rockburst more deeply. but also got the crilicaldepth of plastic softening area of chamber that is valuable in the controlling engineering of rockburst. the chamber displacement jump and energy liberation have been derived. the influence of rock parameters on the rockburst has been discussed.

Key words: nonlinear ordinary differential equation set, transformation set, integrable type, rockburst, CUSP model of catastrophe theory, critical depth ofplastic softening area, displacement jump, energy liberation