Prestressed hollow slab strengthened with CFRP is a new reinforcement method. To study the effect on reinforcement through different carbon fiber paste volume and paste manner, we did the experimental study on flexural capacity under the secondary load conditions with prestressed concrete hollow slab commonly used in engineering. Meanwhile, we also did the contrast analysis of reinforcement effect on the old and new prestressed concrete hollow slab. The results showed that prestressed concrete hollow slab strengthened with CFRP could effectively improve the flexural capacity of the specimen, besides the capacity increasing of the old and new prestressed hollow slab is a little difference, but both of the new and old can meet the engineering design specifications.