Based on the existed stress-strain curve of concrete prism under one-off short-term load and the concrete creep model, a new time-effect model for evaluation of concrete compressive strength is established through the synthesis of the concrete creep attenuating effect under sustained load and the concrete strength enhancing effect by age, a corresponding computer program has been developed. The computation of related indices and their change rules of several different-grade concrete materials with the program was carried out and the results were compared with experimental data and finite element numerical results reported in the literature, the reasonableness and practicality of the proposed new model have been verified.