The present application provides a shoulder strap applicable to a baby carrier, comprising: a strap body having a top end and a bottom end and two sides; and at least one of a decompression expansion member extending outwardly from at least one of the two sides of the strap body, being as long as the strap body, and connected to the top and bottom ends of the strap body, respectively, wherein the decompression extension member has a first extended flap medially extending toward the other one of the two sides of the strap body and a second extended flap extending in a reverse direction to the inner side of the first extended flap, and having an outer side.