Abstract: The article applies a twostep ironic solution reaction to in situ deposit calcium carbonate nanoparticles onto bamboo fibers. The distributions of calcium carbonate nanoparticles at different molarities of calcium chloride ironic solutions and their effects on surface performances of bamboo fibers were investigated, involving surface topography, wetting properties and surface roughness. The results showed that calcium carbonate adsorbances rose from 0.97% to 12.3% and the morphology of calcium carbonate crystals changed from the single, irregularly tetrahedral nanoparticles to spheroplasts or axiolitic particles, as molarities of calcium chloride ironic solutions increased. The size of single crystal was around 60 nm. Calcium carbonate crystals, which filled the micropores of bamboo fibers, were responsible for distinct variances of surface roughness and wetting properties of modified fibers under different molar concentration levels. The average Rq value (234.38) of the treated individual bamboo fibers at the molarity of 0.3 mol/L was at the peak, the average static contact angle of which reached the lowest point of 64.00°.