Aiming at the problem that hot-casting sockets are easy to fail at elevated temperatures due to the low melt point of Zn-Cu alloy （approximately 460 ℃±10 ℃）， high-temperature tensile tests were carried out on the hot-cast anchor sockets of prestressing twisted wire strands to obtain the failure modes and tensile capacity of specimens at elevated temperatures. The ultimate tensile capacity calculation formulas of the hot-cast anchor sockets of twisted wire strands and critical temperature under various load ratios were proposed， which can be used for the fire resistance capacity verification and fire protection layer thickness design of the hot-cast anchor sockets. Test results show that the failure mode is the rupture of the strand when the temperature is lower than 200 ℃， while the failure mode is the pull-out of the strand from the socket when the temperature is greater than 200 ℃. When the temperature is in 150~440 ℃ range， the load capacity of the anchorage decreases as the temperature increases. The load capacity at the anchorage temperature of 287 ℃， 340 ℃， 392 ℃ and 425 ℃ is 77.3%， 39%， 35.2% and 10.5% of that at ambient temperature， respectively.