Abstract: Municipal sewage sludge（MSS） and soil collected in rocky desertification area were used as test materials and indoor pot experiment method was adopted, in which MSS was applied to soil with different proportions, and Pennisetum alopecuroides was planted.The effect of MSS addition on photosynthesis and growth of Pennisetum alopecuroides seedlings was analyzed, in order to provide reference for the resource utilization of municipal sewage sludge.The results showed that the content of soil organic matter, total nitrogen, total phosphorus, available nitrogen and available phosphorus increased significantly, and the content of heavy metals also increased with the increase of MSS addition ratio.When adding 50%-75% MSS,the contents of Cd and Zn in the mixed matrix exceeded the standard of Soil Environmental Quality-pollution Risk Control Standard of Agricultural Land（Trial）（GB15618-2018）.When adding 20%-35% MSS,the transpiration rate, stomatal conductivity, net photosynthetic rate and water use efficiency of Pennisetum alopecuroides seedlings increased with the growth time, but these indicators significantly decreased in 50%-75% MSS addition treatments.The photosynthetic characteristics of Pennisetum alopecuroides seedlings were inhibited and its growth was affected on condition of high proportion of MSS application.Therefore, high proportion of MSS application might lead to soil heavy metal contamination, inhibit plant photosynthetic capacity and affect plant growth.To improve the fertility of soil in rocky desertification areas by MSS application, the proportion should be controlled well, and it should be no more than 50%.