Abstract: The form and structure, the resource, the affect factor and the eliminator of the moss were studied with Sphagnum which was the culture aggregate of butterfly?orchid in greenhouse. The results were showed as follows: (1) The main compositions of the moss were Oscillatoria of the Cyanophyta and Chlamydomonas of the Rhodophyta. (2) Both the culture aggregate-Sphagnum and water were the resource of the moss, and the former was the main. (3) Sphagnum that was covered with moss was treated with shading. Contend of Chlorophyll of the moss reduced gradually as the time lasted. In the first 5 days, reducing speed of contend of Chlorophyll was the fastest. From the 6th day to the 30th day, the reducing speed was slow-quick-slow. (4) The growth of moss was affected by pH. The moss could grow between pH 2.0 and pH 10.0. The chlorophyll content was the highest at pH 3.0, the second was at pH 8.0. It was the lowest at pH 2.0. (5) The moss was restrained with different concentration of KMnO4. The chlorophyll content was the lowest at treatment of 0.2mg/L, but it was still lower than the CK. The inhibition effect was the best at 0.1mg/L.