The present invention relates to a metal sheath inorganic mineral insulation electric cable fire resistance performance testing method, which comprises: S1, selecting an electric cable; S2, carrying out single electric cable fire resistance testing, wherein an electric cable is vertically fixed inside a fire resistance test apparatus, flame is sprayed through a propane burner, the flame length is controlled at 15-20 cm, the distance between the flame and electric cable contact point and the upper end fixation point is 40-50 cm, the electric cable is burned for 10-15 min, and the length of the part damaged by the burning is recorded; S3, carrying out bundle electric cable fire resistance testing, wherein 3-5 electric cables are vertically fixed on a trapezoidal testing frame, the trapezoidal testing frame is placed inside the fire resistance test apparatus, air is introduced, the flow rate is controlled at 60-100 L / min, flame is sprayed through the propane burner, the flame temperature is controlled at 450-950 DEG C, burning is performed for 20-30 min, and the burning condition is recorded; and S4, judging the fire resistance performance, wherein it is judged that the fire resistance performance passes through the testing if the length of the part damaged by the burning in the step S2 does not exceed 30 cm and no burning exists within 20 min in the step S3. According to the present invention, the method has advantages of simple operation, and accurate and reliable testing data.