The water reducer and retarder were adopted to modify the working performance of disqualified fresh concrete, and the modified concrete was mixed into the fresh concrete with a constant mix proportion for recycling. The effect of different placing time(90,180,270min) and replacing rate(10%,20%,30%) were studied by the tests of slump loss through time and compressive strength. According to the results, the slump loss through time of the recycled concrete is similar to the result of fresh concrete within 30minutes but increases rapidly after 60min, the minimum compressive strength of the recycled concrete after 7days was 315MPa with the placing time equal to 180 min and replacing rate equal to 30%, and the minimum compressive strength after 28days is 501MPa with the placing time equal to 270 min and replacing rate equal to 30%. The experiment shows that the disqualified fresh concrete before the initial setting was suitable for the preparation of recycled concrete.