Abstract: A reliability analysis model is established to analyze the stability of a tank based on the tank-roof stability checking formulae and the reliability theory. A new method for calculating and analyzing the reliability and the stability of the tank-roof by the minimum distance and finite difference methods is proposed. The analysis results of the tank as an engineering example by the proposed methods show that the self-supporting role of the roof-plates and the strengthened role of stiffened ribs would affect the reliability index of the tank-roof under different external loads. The curve fitting method is applied for expressing the numerical relationships between the reliability index and affecting factors. A reliability assessment is also performed to show the feasibility of analyzing the stability reliability of the dome roof for storage tanks in service.