On the basis of creep phenomenon in practical construction, with the application of improved equipment the creep behavior and the effects of water cement ratio, contents of fly ash, ground slag and silica fume at early ages were investigated by tensile creep test. By defining sensitivity factor and analyzing the test results, sensitivity analysis was carried out. The results show that the content of silica fume and water cement ratio have a much greater influence on tensile creep than the content of fly ash and ground slag, which will be a good reference for the succeeding research and similar engineering practice．