The study of the shear strain distribution at the bonding interface helped us to understand the bamboo bonding interface response mechanisms to solve problems of ply bamboo deformation or bonding failure. The shear strain distribution across a two-ply bamboo sheet bonded with a ductile phenol-formaldehyde resin (PF) modified by poly(vinyl alcohol) (PVA) was measured by means of electronic speckle pattern interferometry, along with tensile strength measurements to prove the shear stain distribution on a macroscopic scale. This research effectively combined macroscopic mechanical properties with microcosmic interfacial mechanical properties. The shear strength and shear strain results showed that PF modified with 20% PVA performed better than common PF and PF modified with 5 and 10% PVA. Microscopic fluorescent characterization of the bonding interface also provided evidence that a new bonding mechanism was adequate for bamboo bonding under the ductile PF modified with 20% PVA. Moreover, we suppose that the results of this study will help in the choice of bamboo-specific adhesives under different strain conditions. (C) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1345-1350, 2013