Abstract: The article, based on substitution of "elastic antibending twist" modle for analytical calculaion of longitudinal bending load owing to temperature rising, solves the problems is to calculation of internal expansion and displacement of the buried longitudinal elbows with two symmetrical arms with the rise of temperature.Finally, tanking φ720 × 8 oil and gas pipelines for examplcoit shows the whole process of calculation, making a comparison between the result and the literature(4), and brings up some questions as to calculation modle in the literature for further consideration.