Concrete structures may be exposed to high heat. In such a way that high heat in the vicinity of concrete structures causes damage in concrete. The aim of this study is assessment of effect of electric high heat on the bending capacity, energy absorption, fracture type and crack distribution of circular fiber concrete slab under monotonic loading. The concrete aggregates with a fracture percentage of 45% are from the mines around Tehran and the fibers used in the concrete are of macrosynthetic type. The concrete mixing design was based on the target compressive strength of 45 MPa and the amount of fibers equal to 0.5% of concrete volume. The heating of the concrete samples was done by a 2400-liter device with a power of 90 KW and maximum temperature of 550 degrees Celsius. To perform slab tests, Dartec9600 device was used with monotonic loading at a rate 0.004 mm/s. based on the Experimental studies conducted on the fiber concrete slab, the application of high heat did not cause concrete peeling but it reduced the capacity of the slab by 89.3% and decreased the energy absorption of the slab compared to the control sample. Also, SEM photos have shown the aggressive destruction of macrosynthetic fibers and the creation of cracks under the effect of high heat in fiber concrete. پرونده مقاله