The results show the performance of straw particleboards is highly dependent upon the straw particle size. The results show the performance of straw particleboards is highly dependent upon the straw particle size. The static bending and internal bonding strength of pMDI resin-bonded boards initially increases then decreases with decreased particle size. The LE, TS and WA of particleboards decrease with increasing particle size. Compared with pMDI resin-bonded panels, UF resin-bonded particleboard exhibits much poorer performance due to the poor compatibility between rice straw and UF resin. The best panel properties obtained in this study can meet class M-2 requirement in ANSI Standard for Wood Particleboard.