The invention discloses a method for detecting durability of an overflow brick. The detection method comprises the following steps of: horizontally placing a rectangular to-be-detected overflow brick into a high temperature resistant container in a manner of being vertical to the height direction, respectively placing two lengthwise ends of the to-be-detected overflow brick onto two supporting bases, so as to ensure that creep spaces are formed at the lower surface of the to-be-detected overflow brick and the bottom of the high temperature resistant container; performing high-temperature erosion treatment on the to-be-detected overflow brick in a vitreous humor so as to enable the overflow brick to creep downwards in the height direction, thereby obtaining the creep overflow brick; calculating the high temperature creep rate sigma of the overflow brick by use of a formula I, wherein the formula I is as shown in the description; the lower the high temperature creep rate sigma is, the better the durability of the to-be-detected overflow brick is. The detection method disclosed by the invention is capable of detecting the high temperature creep rate of the overflow brick so as to detect the durability of the overflow brick.