The invention discloses a prestressed concrete hollow plate reinforcing device and method. The device comprises a prestressed concrete hollow plate and an unbonded steel strand for reinforcing the prestressed concrete hollow plate. The unbonded steel strand penetrates into a hollow hole of the prestressed concrete hollow plate from one end of the prestressed concrete hollow plate, and the unbondedsteel strand penetrates out of a reinforcing hole in the other end of the prestressed concrete hollow plate after steering through a steering block. The two ends of the unbonded steel strand are anchored to support beams of the prestressed concrete hollow plate through anchoring devices. According to the prestressed concrete hollow plate reinforcing device and method, the aim of improving the bearing capacity of the prestressed concrete hollow plate is achieved without increasing the dead weight and section height of the prestressed concrete hollow plate. Due to the fact that the prestressedconcrete hollow plate can be reinforced simply on the plate face, the limitation that according to an existing reinforcing method, the plate bottom needs to be reinforced is solved, and certain special needs are met. In addition, the device and method are clear in reinforcing structure stress, convenient to construct, short in construction period and low in reinforcing cost, and have high application value.