A prosthetic knee joint with buffering and braking effects has an upper connecting base (10), a linking assembly (20), a braking assembly (30), and a lower connecting base (40), which form a four-bar linkage. The upper connecting base (10) has two extending lugs (11) and an accommodating recess (12). The linking assembly (20) has two linking arms (21) respectively and pivotally connected to the upper connecting base (10). The braking assembly (30) has a braking arm (31) protruding into the accommodating recess (12) and pivotally connected to the two extending lugs (11). The lower connecting base (40) is connected to the linking assembly (20) and the braking assembly (30). A cushion (43) provides a buffering effect during walking. Thus, the prosthetic knee joint has simplified structure and reduced cost and is convenient in assembly and use.
