Abstract: In order to study the material time-dependent performance of early age concrete, the relationship between the early age concrete elastic modulus and the maintain time were obtained by 24 sets of standard prismatic concrete specimens which were made in construction site, and by synchronous maintenance in the deck. Then the function formula between them was optimized. The elevation control reliability model was established based on SVM (support vector machine), the reliability index were calculated by Monte Carlo method. The result shows that power function describes the relationship between the curing time and the elastic modulus of early age concrete. The cantilever stage and the maximum cantilever stage is controlled by different allowable deviation of deflection. To middle cantilever stage, the maximum allowable value of the free end deflection is not higher than 4 mm, while the maximum allowable value of the maximum cantilever stage is not higher than 20 mm.