Based on the interval descriptions of the uncertain parameters, use the method of degree to analyze the structural interval reliability. Use interval numbers to descript the uncertainty of which affect the structural function, and establish the interval stress - interval strength interference model of structural reliability analysis, the interval variability will be introduced to the interval reliability analysis. Based on interval mathematics and the theory of the interval comparative method, this paper proposes a new interval reliability index, use research of interval structural reliability analysis based on degree method to calculate. Example from engineering demonstrates the feasibility and effectiveness of this method.