Method of manufacturing cellulose nano-fibres from stalks of annual plants characterized by that pieces of annual plants stalks 10-70 mm long are subjected to processing in following steps: a) action of water steam at pressure of 1,5 - 3 bar during 5-60 minutes b) mechanical defibrillation for 3 to 10 minutes in a disk mill c) digestion for 60 to 120 minutes at temperature of from 110 to 160°C in a pulping liquor with 5 -15 wt% content of NaOH calculated on dry mass of the stalks, at liquid module of from 3:1 to 8:1 d) oxygen delignification in aqueous medium containing 2 - 4 wt% of NaOH and 0,2 - 0,5 wt% of MgSO 4, on dry mass; process conditions: oxygen pressure at start 0,2 - 0,5 MPa, concentration of mass 8 -15wt% wag., time 60 - 120 minutes, temperature 110 - 120°C e) bleaching, at least twice, with sodium chlorite at NaClO 2 concentration of 1 - 1,5wt% and H 2 SO 4 concentration of 0,05 - 0,1wt% at temperature of 60 - 70°C for 60-120 minutes, followed by alkaline extraction in aqueous NaOH with concentration of 0,5 - 1wt% at temperature of 70 - 80°C for 60-120 minutes f) enzymatic treatment of the prepared cellulose pulp with cellulase at activity of endo-1,4-beta-glucanase of 10-1000 J/g on dry mass, at pH of 4 - 7, at temperature of 40 - 60°C, for 30-480 minutes, with agitation of 50 - 500 rpm followed by washing of the cellulose pulp with demi water, and vacuum filtration, and deactivation of the enzyme residual in the pulp at temperature of 90 - 125°C for 10 - 30minutes g) homogenizing of the aqueous cellulose suspension with concentration of 0.5-3wt%, at agitation speed of 5000 - 20000 rpm for 1 - 10 minutes, wherein during the agitation, the suspension is quenched with refrigeration brine at about -15°C, wherein next the suspension is centrifuged at 4000 - 15000 rpm for 5 - 30 minutes to obtain a supernatant containing cellulose nano-fibres. a) action of water steam at pressure of 1,5 - 3 bar during 5-60 minutes b) mechanical defibrillation for 3 to 10 minutes in a disk mill c) digestion for 60 to 120 minutes at temperature of from 110 to 160°C in a pulping liquor with 5 -15 wt% content of NaOH calculated on dry mass of the stalks, at liquid module of from 3:1 to 8:1 d) oxygen delignification in aqueous medium containing 2 - 4 wt% of NaOH and 0,2 - 0,5 wt% of MgSO 4, on dry mass; process conditions: oxygen pressure at start 0,2 - 0,5 MPa, concentration of mass 8 -15wt% wag., time 60 - 120 minutes, temperature 110 - 120°C e) bleaching, at least twice, with sodium chlorite at NaClO 2 concentration of 1 - 1,5wt% and H 2 SO 4 concentration of 0,05 - 0,1wt% at temperature of 60 - 70°C for 60-120 minutes, followed by alkaline extraction in aqueous NaOH with concentration of 0,5 - 1wt% at temperature of 70 - 80°C for 60-120 minutes f) enzymatic treatment of the prepared cellulose pulp with cellulase at activity of endo-1,4-beta-glucanase of 10-1000 J/g on dry mass, at pH of 4 - 7, at temperature of 40 - 60°C, for 30-480 minutes, with agitation of 50 - 500 rpm followed by washing of the cellulose pulp with demi water, and vacuum filtration, and deactivation of the enzyme residual in the pulp at temperature of 90 - 125°C for 10 - 30minutes g) homogenizing of the aqueous cellulose suspension with concentration of 0.5-3wt%, at agitation speed of 5000 - 20000 rpm for 1 - 10 minutes, wherein during the agitation, the suspension is quenched with refrigeration brine at about -15°C, wherein next the suspension is centrifuged at 4000 - 15000 rpm for 5 - 30 minutes to obtain a supernatant containing cellulose nano-fibres.