Abstract: Studied here in the paper is the effect by the heat treatment temperature on the grain size and mechanical properties of the TP317L hot-extruded furnace tube. As a result it is revealed the facts as follows. The grains of the head and tail parts the as-hot-extruded TP317L furnace tube are finer than those at other positions thereof. Along with the increase of heat treatment temperature,the grain size is gradually enlarged,and the size enlargement rate of the tube head and tail grains is more significant;and with the increase of the temperature,the strength of the head and tail of the TP317L furnace tube is gradually decreased,while the strength of the middle position of the tube gets increased first and then decreased;as for the hardness of the tube it gets decreased also with the rise of the heat treatment temperature.The TP317L hot-extruded furnace tube as heat-treated at 1 060℃ presents as a whole rather satisfactory mechanical properties.