The invention relates to endogenous sphingosine monas sourced from pennisetum purpureum and an application thereof and particularly relates to a separation and cultivation method of the plant endophyte sphingosine monas which promotes the growth and development of hybridized Chinese pennisetum and an application of the endophyte sphingosine monas in promotion of growth of seedlings of the hybridized Chinese pennisetum. The invention belongs to the technical field of microorganisms of agricultural application. The endogenous sphingosine monas is a pennisetum purpureum endophyte strain pp01 with a classification name of sphingosine monas genus Sphingomonas sp. pp01 and is preserved in China General Microbiological Culture Collection Center at 2014 Jul.4 with the accession number of CGMCC 9414. The strain is an excellent plant-growth-promoting endophyte strain, has the characteristics of producing IAA, fixing nitrogen and producing iron carriers and has an excellent colonization capability at the roots of plants. By means of the strain for infecting the hybridized Chinese pennisetum, the plants are significantly improved in resistance against salt stress and are promoted in growth and development. Compared with a non-inoculated negative control group, fresh weight of overground part of the plants is increased by 101.1%, dry weight is increased by 138.6% and the height of the plant is increased by 42.4%. The invention can be used for promoting the growth and development of plants in saline and alkaline marginal land, and has important effect in research of microorganism fertilizers and utilization of saline and alkaline marginal land sources.