The article presents the results of the study on the chitosan extracting procedure from freshwater crab shell to produce a good quality of chitosan and efficient utilization of freshwater crab by-products as well. The study consisted of four experiments including (i) the effects of HCl concentration (8, 10 and 12%) and treatment time (15, 17 and 19 hours) on remain ash content; (ii) the effects of NaOH concentration (30, 40 and 50%) and treatment time (4.5, 5.5 and 6.5 hours) on remain protein content; (iii) the effects of decoloring time (15,30, 45, 60 and 75 minutes) on L* value; (iv) the effects of drying time (24, 48, 72 and 96 hours) at 55^oC on moisture content and yield of extracted chitosan. The results showed that protein and ash contents of chitosan from freshwater crab shell were 5.73% and 0.58%, respectively as 10% HCl and treatment time for 15 hours and deashing twice; 40% NaOH and treatment time for 5.5 hours were applied. The best L* value was 59.74 as applying a decoloring time for 45 minutes. The best moisture content and yield of extracted chitosan were 9.37% and 20.13%, respectively as chitosan solution dried for 48 hours at 55^oC. Viscosity (143.5 mPas) and dissolubility (99.9%) of extracted chitosan from freshwater crab shell showed higher than viscosity (132.5 mPas) and dissolubility (99.7%) of commercial chitosan from black tiger shrimp shell.