Abstract: A novel automatically step-up method (ASUM) to analyze creep and shrinkage effects at any time is presented. The relationship between stress and strain of concrete in prestressed concrete bridges is written as algebraic form within load duration and the equilibrium equations of internal force and compatibility conditions are introduced. The influences of sectional characteristics, steel arrangement, steel ratio, stress losses of tendons and the change of concrete modulus with time are considered, and various expressions of creep and shrinkage are allowed for based on the established equations, it is easy to calculate both total stresses and strains of concrete and steel and total deflection of bridge. Comparison between theoretical values and experimental data shows that agreeable results will be obtained by easy precision control through further dividing the time period. The method in this paper can be computerized and incorporated into nowadays commonly-used software packages for bridge structural analysis to perform reliable creep analysis.