Aimed at the unfavorable impact of mono-cropping cultivation on farmland environment,in paddy field,a five-year field experiment was carried out.Ecological analysis in the experiment was conducted to compare crop rotation with mono-cropping cultivation in soil physical and chemical properties,yield,incidence of crop diseases and pests,energy flow and nutrient balance.The results show that the former significantly improved soil physical and chemical properties and yield by 384.8%,226.2% and 3.0%,respectively.Moreover,crop rotation not only altered the environment for pathogen bacteria, but also built up plant resistance to diseases and pest,and suppressed crop diseases,insects,and weeds,etc.and increased the overall initiative productivity,light energy use rate and auxiliary energy use rate by 17.47%,9.87% and 5.0%,respectively,N,P and K use rate as well.Therefore,reasonable optimized multi-crop rotation systems are presented in the paper.