The dynamics of four-order modified Chua's circuit with slow-fast effect has been investigated in this letter. Different types of bursting phenomena can be observed in numerical simulations. By introducing slow-fast analysis, the bifurcation mechanism for the periodic bursting solutions, especially for Fold/Fold bursting and Fold/Hopf bursting, is presented, which is different from the usual case. With the variation of the parameter, the periodic bursting can evolve to chaotic bursting.