NOVELTY - An electrolyte material lanthanum silicate powder is prepared by adding nano silicon dioxide (SiO2) powder into water, blending prepared nitrate saturated solution and nano SiO2 suspension, adding premixed liquid of organic monomer acrylamide (AM) and crosslinking agent N,N'-methylenebisacrylamide (MBAM), adding evocating agent ammonium persulfate (APS), adding dropwise aqueous solution of APS, placing the mixture at constant 60-80 degrees C for 30-80 minutes, curing to obtain an in-situ gel, dehydrating and pretreating the gel to produce a dark grey precursor, and calcining precursor.    USE - Preparation of electrolyte material lanthanum silicate powder for intermediate temperature solid oxide fuel cell (claimed).    ADVANTAGE - The electrolyte material lanthanum silicate powder has higher purity.    DETAILED DESCRIPTION - Preparation of electrolyte material lanthanum silicate powder comprises:    (A) adding nano SiO2 powder into water to obtain a uniform suspension, blending prepared nitrate saturated solution and nano SiO2 suspension, and uniformly stirring;    (B) adding premixed liquid of organic monomer AM and crosslinking agent MBAM, uniformly stirring, adding evocating agent ammonium persulfate (APS, 1-2 wt.%) into the mixture, adding dropwise aqueous solution of APS (2-4 wt.%), and uniformly stirring; and    (C) placing the mixture at constant 60-80 degrees C for 30-80 minutes, curing to obtain an in-situ gel, dehydrating and pretreating the gel at 300-400 degrees C to produce a dark grey precursor, and calcining precursor for 5-15 hours at 1200-1400 degrees C to obtain the product.    The raw materials are lanthanum nitrate hexahydrate (La(NO3)3.6H2O) and nano SiO2; La(NO3)3.6H2O, nano SiO2 and strontium nitrate; La(NO3)3.6H2O, nano SiO2 and barium nitrate; La(NO3)3.6H2O, nano SiO2 and aluminum nitrate nonahydrate; or any other raw materials which can synthesize lanthanum silicate electrolyte powder doped at lanthanum-position and/or silicon-position. A total mass of added organic monomer and crosslinking agent premixed liquid is 10-60% of total mass of raw materials.