As a superconducting material, Bi 2233/Ag tape needs high-critical transport current density J(c), which is influenced by the uniform deformation and density of BSCCO powder in filaments during the forming process. The aim of this paper is to investigate the constitutive behaviour of BSCCO powder. The modified Drucker-Prager/Cap model is introduced to describe the constitutive behaviour of BSCCO powder. A series of cyclic loading experiments for BSCCO powder in a cylinder die were carried out. Based on the experiments, the relationships between the radial stress and the axial stress were obtained, and the parameters in the constitutive model were calculated. By pushing the compact powder from the die, the coefficient of friction between the BSCCO powder and the cylinder die was determined. Finally, the modified Drucker-Prager/Cap model is proposed and used to simulate the confined compression test of BSCCO powder.