The invention discloses a composting material composition, which comprises city domestic sludge, water hyacinth and food waste, and the weight proportion of city domestic sludge to water hyacinth to food waste is 3-7:2-6:2-8, wherein the water content of the composition is controlled to be 50%-55%, and the ratio of C to N is 23:1-30:1. The composting method comprises the following steps: after composting raw materials are hermetically fermented, fermenting the composting raw materials by forced ventilation, and fermenting the composting raw materials by natural ventilation. The composting method provided by the invention has high organic matter degradation rate which is higher than 40%; the pH value does not need to be regulated; and various condition parameters are stable controllable factors, thereby further improving the practicability, the controllability and the stability of the method of the invention. The invention has wide application prospects.