We prepared Ag-sheathed Bi system tape by the stuff with compression molding powder-in-tube method. Ag-sheathed tape of Bi system superconductors were studi-ed for sample with nominal composition of Bi_1.8Pb_0.4Sr₂Ca_2.2Cu₃O_y. The critical current density of sample apparently depended on the thickness of the tape and increased markedly with decreasing tape thickness. The maximum value of the critical current density of sample 6.1×10⁵A/cm² at 6 K in zero magnetic field was achieved in a tape with 0.3 mm thickness and at 77K were 1.4×10⁴A/cm² in zero magnetic field.