The invention relates to the technical field of bridge engineering, in particular to a concrete creep strain calculation method. The method comprises the following steps that 1, a creep coefficient phi(t, tau0) of concrete from the moment tau 0 loaded to the moment t and an elasticity modulus E(t, tau 0) are calculated; 2, an elasticity modulus E(t, tau 0) of concrete from the moment tau 0 loaded to the moment t is calculated; 3, according to the steps 1 and 2, a concrete creep strain calculation equation is obtained, and the equation is applied for calculating concrete creep strain, the calculation equation is shown in the description, the elasticity modulus E(t, tau 0) is obtained according to an aging coefficient, the elasticity modulus E(t, tau 0) is an effective modulus adjusted according to ages, and the expression is shown in the description. According to the method, the modulus is reduced, deformation modulus caused by concrete creep is achieved, strain changing along with time can be applied to concrete in one step, and therefore the problem that an effective modulus method overstates creep strain caused by stress increment obtained after loading is performed for the first time is solved.