The purpose of the research work was to determine the influence of the particle size in the extraction of cellulose from the Calamagrostis Intermedia species, since the extraction and commercialization of cellulose is one of the most versatile industries, however, the use of wood sources leads to an environmental impact that cannot be mitigated, considering that in extractive processes there is no rationing of resources within washing or bleaching. The analysis of the particle size of a non-timber endemic species of Ecuador was proposed, considering a pretreatment of the samples with a study of drying, grinding and screening after the taxonomic identification, an alkaline extraction was applied simulating the industrial conditions at the laboratory level. with the samples of defined particle size with an experimental design 22, to give way to the characterization of the extracted cellulose. It was determined that the particle size influences the amount of fiber mass and cellulose pulp extracted in the samples previously dried at 65°C and with particle sizes of 300 and 106 μm. Characterization tests reveal a variation in the color and texture of the extracted cellulose, caused by an inefficient delignification step within the fiber bleaching, variations in molecular weight corresponding to 126.32 x 103 g/mol between the samples, FTIR analysis shows a syringyl ring and stretching in lignin, light microscopy reveals the absence of well-defined regions in the fibers and an easily discernible crystal lattice.