In view of such flaws as low intensity and poor plasticity found in Zn-based alloys used as biodegradable cardiovascular scaffold, biodegradable Zn-3Cu-xMn (x is mass fraction of Mn of 0%,0.5%,1%,1.5% respectively) alloy bars are prepared by alloying and hot extrusion, followed by a research on the relationship between the content of Mn in the alloy and its microstructure, mechanical properties and degradation properties. The results show that the alloy is composed of Zn matrix and CuZn5 second phase; when the content of Mn exceeds 1%, MnZn13 phase appears in the alloy. With the mass fraction of Mn content in the allot increasing from 0 to 1.5%, correspondingly the yield strength of the alloy increases from 138 MPa to 198 MPa, the tensile strength increases from 231 MPa to 355 MPa, while the elongation decreases from 96.2% to 39.0%. Meanwhile, the degradation rate of the alloy increases from 0.13 mm/a to 0.49 mm/a in vitro.