Waterlogged archaeological catalpa wood uncovered from Changtaiguan was tentatively treated by gradient dehydration of ethanol concentration, replacement of PEG200DMA gradually, and ,60,Co γ-rays radiation curing with absorbed dose 30.72 kGy at dose rate 90.35 Gy/min. It can be found that the color and appearance of reinforced archaeological wood with clear texture looks like original one. There is no cracking, no warping, and no glare on the wood surface. The Compression strength of reinforced ancient wood (33.06 MPa) is close to that of modern Catalpa wood. The maximum linear shrinkage of reinforced ancient wood is 1.05% in grain direction, 4.10% in radial direction, and 4.32% in tangential direction respectively compared with that of original sample. The linear shrinkage under the condition of 180 days storage in the ambient temperature and humidity is 0.076% in grain direction, 1.17% in radial direction, and 1.86% in tangential direction respectively. The linear shrinkage under the condition of 90 days storage in the temperature (25±2) ℃ and relative humidity (5±2)% is 0.066% in grain direction, 0.115% in radial direction, and 0.279% in tangential direction respectively. The linear swelling ratio after 90 days storage in the temperature (25±2) ℃ and relative humidity (98±2)% is 1.79% in grain direction, 2.42% in radial direction, and 2.61% in tangential direction respectively. It is confirmed by microstructure study that capillaries in residual wood has been filled with polymers, so that the wood mechanical strength and the shape stability is improved respectively.