Abstract: 1.The process of Stanford, Le Gloahec-Herter and Green was investigated and the following improvements were made to obtain a suitable process for extracting the alginic acid from the seaweed of domestically produced Sargassum: 1) lixiviation of kelp with 0.8—1.0% calcium chloride solution is omitted; 2) duration for the preliminary decolorization of kelp with formadehyde solution is shortened from 20 days originally needed to 4—7 days, while the concentration of formadehyde is increased from 0.1 to 1%; 3) concentration of the digestion solution (soda solution) is changed, from 4.0% employed by Le Gloahec-Herter to 2.0%, while the duration of digestion is increased to 4—8 hours. 2.The effect of drying temperature on the viscosity of the salt of alginic acid has been investigated: ammonium alginate, after being dried at 60, 70, 80, 90, 100℃ for four hours respectively, loses its viscosity by 10—20% (in centipoises) with every increase of the temperature ranges. (the original sample having a viscosity around 100 centipoises). 3.Ammonium alginate produced by this process is somewhat coloured and has a viscosity of 20—140 centipoises, but that obtained from fresh kelp of Sargassum has a viscosity of 16000 centipoises. 4.The quality of sodium alginate prepared by this process conforms well with the requirements of the "National Formulary."