The work aims to scientifically evaluate the mechanical properties of oriented strand board (OSB). The mechanical properties of OSB specimens were measured under five loading speeds in the three point bending method based on GB/T 17657—2013. The in-plane strain distribution of the specimens was recorded with digital image correlation (DIC) synchronously. The results showed that, based on the loading speed selected in the study, it was found that, although the increase of the loading speed could improve the elasticity modulus and the maximum load measurement value to a certain extent, the effect was not obvious. The variation of intrinsic mechanical properties of OSB was obviously greater than the effect of loading speed on mechanical properties. The variation of the maximum displacement of the sample increases under the maximum loading force when loading time is larger or smaller than (60±30) s given in the national standard. The strain distribution in OSB sample is not completely in consistency with the well-known beam bending theory and laminated panel theory.