The effects of mercerization, traditional silanization and a sol-gel treatment on hemp primary processing waste particle size distribution after grinding with 1mm grid and composite maximal tensile strength correlation with waste particle distribution were investigated. The waste was shaken in a sieve shaker by the standard LVS EN 933 (111) using 1000 µm, 500 µm, 355 µm, 150 µm, 90 µm sieves. Composites with the fibre content 40 wt% using LLDPE as a matrix were prepared by two roll mill. A correlation between the waste particle size and the maximum tensile strength of the composite was found - lower maximum tensile strength shows composite with modal fibre size distribution smaller than 90 µm. With hemp waste particle distribution composite maximum tensile strength differences can be predicted depending on the waste treatment methods.