In this study, the addition of natural fibers to biodegradable PCL, PLLA blend and the effect of ionizing radiation on the surface of composites were investigated by force modulation microscopy (FMM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Hot pressed sheets were prepared using pellets of twin extruded PCL:PLLA 20:80 (w:w) blend containing 5% or 10% weight concentration of coconut fiber. In this study coconut fibers non treated chemically and acetylated ones were used. Irradiation was performed using an electron beam (EB) accelerator and an absorbed dose of 100 kGy. FMM images acquisition was obtained using a silicon cantilever, intermittent contact mode (tapping mode). Also, AFM images were obtained using tapping mode but J scanner. By FMM, it was possible to observe regions with different elasticity indicating fiber presence under the surface of the composite. Furthermore, it appears that the spherical structures size decreased on composites. This probably was induced by ionizing radiation.