The effects of quasi-hydrostatic pressure treatments on the Bi-system superconductors were investigated The cold-pressing treatments seriously weakened the inter-granular weaklinks and induced a large number of intragranular defects, resulting in the deterioration of the suprcon-ducting properties. The targe increase in the bulk density and the orientation of the superconducting grains were also observed in the cold-pressed samples. These drastic changes of superconductivity were mainly due to the shear stress under quasi-hydrostatic pressure. The post annealing treatments greatly enhanced the weaklinks and caused the partial recovery and the agglomeration of some defects. By coldpressing-annealing method, Jc (77 K, zero field) was raised to about 1600A/cm2. The pressure dependence of Tc under hydrostatic pressure was also investigated and dTc/dp was found to be 1.4K/GPa.