Abstract: Crack tip opening displacement (CTOD)is related with Young's modulus, yield strength, geometrical shape, loading conditions and so on. It has been shown that many properties of structural steel varies with temperature, so the change of temperature will also change the value of CTOD. Tensioned infinite plate with a center crack is used to derive the equation for the variation of CTOD with temperature using Dugdale and Barrenblett's model (D-B model). The analysis is extended to three points bending specimen with a center crack. Finite element calculations and experimental investigations for three-point bending specimen at low temperature were carried out, and the results are compared with the theoretical prediction. Results show that CTOD decreases as temperature drops, and the influence of temperature is related with plasticity status at the crack tip area.