In thispaper，the nutrient management of 51greenhouses，spring and autumn sheds in 22 villages in the 3 mainwatermelon producing areas in Beijing was investigated. Soil organic mattercontent，nutrientcontent，pH，electricityconductivity(EC)，microorganisms and the contents of phenolic acid substances were analyzed to determine the impact of watermelon continuous cropping obstacle factors by principle component analysis. The results showed that chemical fertilizeramount seriously excessive，organic fertilizer mainly based on livestock manure and random addition of fertilizer applications， was very common during production. Most of the soil fertility in the main watermelon producing areas belonged to the classesof medium to highfertility，with significant nutrients enrichment and obviousacidification，saltsaccumulation，microbial community disorder and phenolic acid accumulation. The order of watermelon continuous cropping obstacle factors affectedby soil factors wereactinomycetes，fungi>availablephosphorus，phenolicacid>pH，EC>bacteria，available potassium.Therefore，the main obstacle for watermelon continuous cropping was the result of combined causes of soil microbialimbalance，phosphorus and potassium enrichment，total phenolic acid substances accumulation，soil acidification and secondary soil salinization.