TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preparation (claimed): Preparing inorganic /organic nanometer composite solid electrolyte comprises: (a) preparing the houghite nanometer piece LDHNS, dissolving the M2+ dissolubility salt and M3+ dissolubility salt in the de-ionized water without carbon dioxide (CO2) in the rate of 2:1-4:1 and preparing the mixed salt solution, controlling the concentration of the M2+ is 0.10-1.60 mol/L, dissolving the sodium hydroxide (NaOH) and M2+ in the de-ionized water without CO2 in the rate of 5:1-10:1 and preparing the aqueous alkali of 0.50-10.0 mol/L, dissolving the lactic acid in the de-ionized water without CO2 according to the amount of 2-10 times of the mol number, preparing the lactic acid solution of 0.20-16 mol/L, dropping the mixed salt solution and aqueous alkali to the lactic acid solution in the protecting of N2, the pH value of the system is 8-12 in the dropping process, then crystallizing the slurry for 2-24 hours in the temperature of 40 to 100 centigrade, obtaining the houghite nanometer of lactic acid intercalation, cleaning the lactic acid intercalation, with the de-ionized water without CO2, then centrifugally separating it for 5-20 minutes in the rotating speed of 8000-10000 turns/min, removing the supernatant, cleaning the solid deposit and cleaning it with the de-ionized water without CO2, going on centrifugally separating at high speed, repeating the cleaning, centrifugally separating it until the pH value is 7-7.5, reflowing the solid deposit after the centrifugally separating at high speed for 8-10 hours, obtaining the LDHNS sol, regulating the concentration of 1-10 g/L; and (b) preparing the inorganic /organic nanometer composite solid electrolyte, weighting the PEO and LiClO4 according to the rate of 4:1-12:1 of PEO and LiClO4, dissolving them in the de-ionized water, scattering them for 20-60 minutes using ultrasonic, preparing them as the mixed solution of 12.4-19.8 g/L of PEO and LiClO4, weighting the LDHNS sol with corresponding volume in the mixed solution of PEO and LiClO4, scattering them for 20-60 minutes in the rotating speed of 1000-4000 turns/minute using the interior contact homogenating machine, making them evenly to be mixed, decompressing and vaporizing the solvent of the prepared mixed solution, when the solution is stick, dropping it in the polyfluorotetraethylene die, drying them as film in the temperature of 60-100 degrees C, and obtaining the composite solid electrolyte. Preferred Components: The chemical compound general expression of the houghite nanometer piece LDHNS is (M2+1-xM3+x(OH)2)-x+.M2+=Mg2+, Zn2+, Ni2+, Fe2+, or Co2+;M3+=Al3+, Cr3+, Fe3+, V3+, Co3+, Ga3+, Ti3+;x+=positive charge taken by houghite nanometer piece LDHNS; andx=0.2-0.4.M2+ is bivalence metal ion, and M3+ is three-valued metal ion. Preferred Salts: In (a), the solubility salt of Mg2+ is Mg2+, Zn2+, Ni2+, Fe2+ or Co2+, and the solubility salt of M3+ is Al3+, Cr3+, Fe3+, V3+, Co3+, Ga3+, Ti3+. Specifically, the solubility salt of Mg2+ is Mg(NO3)2, and the solubility salt of Mg3+ is Al(NO3)3.