A method for power headroom, PH, calculation, performed by a terminal, characterized in that the method comprises: receiving (201,301) a path loss reference change indication, wherein the path loss reference change indication is used to indicate changing a first path loss reference to a second path loss reference; and calculating (202,302) a PH by using a specific path loss reference; wherein the specific path loss reference comprises: a path loss reference corresponding to a second time, wherein the second time is a time at which the terminal generates a protocol data unit, PDU, comprising a power headroom report, PHR, or a specified time before a reporting moment of the power headroom report PHR, wherein the specified time is after the time at which the terminal generates the PDU comprising the PHR; wherein if a receiving time of the path loss reference change indication is before the second time, the path loss reference corresponding to the second time comprises: a changed path loss reference indicated by the path loss reference change indication; or if the receiving time of the path loss reference change indication overlaps with the second time, the path loss reference corresponding to the second time comprises: a path loss reference received before receiving the path loss reference change indication, or a changed path loss reference indicated by the path loss reference change indication. receiving (201,301) a path loss reference change indication, wherein the path loss reference change indication is used to indicate changing a first path loss reference to a second path loss reference; and calculating (202,302) a PH by using a specific path loss reference; wherein the specific path loss reference comprises: a path loss reference corresponding to a second time, wherein the second time is a time at which the terminal generates a protocol data unit, PDU, comprising a power headroom report, PHR, or a specified time before a reporting moment of the power headroom report PHR, wherein the specified time is after the time at which the terminal generates the PDU comprising the PHR; wherein if a receiving time of the path loss reference change indication is before the second time, the path loss reference corresponding to the second time comprises: a changed path loss reference indicated by the path loss reference change indication; or if the receiving time of the path loss reference change indication overlaps with the second time, the path loss reference corresponding to the second time comprises: a path loss reference received before receiving the path loss reference change indication, or a changed path loss reference indicated by the path loss reference change indication. a path loss reference corresponding to a second time, wherein the second time is a time at which the terminal generates a protocol data unit, PDU, comprising a power headroom report, PHR, or a specified time before a reporting moment of the power headroom report PHR, wherein the specified time is after the time at which the terminal generates the PDU comprising the PHR; wherein if a receiving time of the path loss reference change indication is before the second time, the path loss reference corresponding to the second time comprises: a changed path loss reference indicated by the path loss reference change indication; or if the receiving time of the path loss reference change indication overlaps with the second time, the path loss reference corresponding to the second time comprises: a path loss reference received before receiving the path loss reference change indication, or a changed path loss reference indicated by the path loss reference change indication.