NOVELTY - Method for preparing environment-friendly liquid compound fertilizer by using cattle excrement sewage, comprises e.g. dry-wet separating and precipitating the fresh cattle excrement to obtain excrement sewage via a second precipitation, fermenting the liquid in a unpowered fermentation system, after fermentation, concentrating the liquid having a original volume of 1/2, 1/3, 1/4, 1/5, 1/10 or nonconcentrating, then filtering, adjusting the pH value of the filtered liquid to 5.5-9, and finally packaging into bags to obtain the finished product.    USE - The method is useful for preparing liquid compound fertilizer, which is useful in livestock environmental pollution control, and waste recycling and resource development.    ADVANTAGE - The method provides liquid compound fertilizer, which is environmental friendly. No biological data given.    DETAILED DESCRIPTION - Method for preparing environment-friendly liquid compound fertilizer by using cattle excrement sewage, comprises: either dry-wet separating and precipitating the fresh cattle excrement to obtain excrement sewage via a second precipitation, fermenting the liquid in a unpowered fermentation system, after fermentation, concentrating the liquid having a original volume of 1/2, 1/3, 1/4, 1/5, 1/10 or nonconcentrating, then filtering, adjusting the pH value of the filtered liquid to 5.5-9, and finally packaging into bags to obtain the finished product; or dry-wet separating and naturally precipitating the cattle excrement sewage, putting the dry-wet separated or precipitated excrement sewage into a second precipitation pool, filling the precipitated liquid into a fermentation tank, adding proper amount of fermentation bactericide, concentrating the obtained fermented liquid by condensing system or nonconcentrating, determining adding mineral nutrient to the purpose of use, then filtering, adjusting the pH value of the filtered liquid to 5.5-9, and packaging into bags to obtain environment-friendly liquid compound fertilizer.