Effect of phosphorus supply on growth, nutrient content and related physiology of Rosa roxburghii seedlings were studied, which was helpful to understand the characteristics of adaptation to low phosphorus stress of R. roxburghii Tratt. seedlings. We used R. roxbunghii seedlings of ‘Guinong 5’ as materials and used cultivating quartz sand and vermiculite mixed matrix as cultivating method. The effect of different phosphorus supply levels on growth, root morphological characteristics, the activity of acid phosphatase (APase)，nitrate reductase (NR) in roots and leaves and secreted acid phosphatase (SAPase) in roots, the species and content of small molecular organic acids in roots, and the content of nutrient elements in plants of R. roxburghii seedlings were studied. The results showed that: (1) The growth of R. roxbunghii seedlings was inhibited when the supplying level of phosphorus was lower or above 45 mg·L^-1 than，with a significantly reduced biomass, total root length, total root surface area, total root volume, average diameter, total root tip number of R. roxbunghii seedlings. The rootshoot ratio, the root hair density and length of R. roxbunghii seedlings reached the maximum at 5 mg·L^-1 phosphorus level, those 3 indexes was decreased with the increasing of phosphorus supply level. (2) The activity of APase in roots and leaves and SAPase in roots of R. roxbunghii seedlings decreased with the increase of phosphorus level. The contents of oxalic acid, tartaric acid, citric acid, malic acid, acetic acid and succinic acid in roots of R. roxbunghii seedlings decreased with the increase of phosphorus level. The activity NR in leaves and roots of R. roxbunghii seedlings reached the maximum at 45 mg·L^-1 phosphorus level, the activity of NR in leaves and roots decreased obviously when the phosphorus level was less than or greater than that. (3)The contents of P, Ca and Mg increased of R. roxbunghii seedlings with the increase of phosphorus level, the contents of Zn decreased with the increase of phosphorus level. The contents of N, P, K, Mn, Cu and B of R. roxbunghii seedlings reached the maximum at 45 mg·L^-1 phosphorus level, the content of these elements decreased obviously when the phosphorus level was less than or greater than that. The studied showed that too low or too high phosphorus supply had adverse effects on growth and nutrient absorption of R. roxburghii seedlings. The increased of root hair length and density, the enhanced activity of APase in leaves and roots and SAPase in roots, the increased contents of small molecular organic acids were the important adaptation strategies for the R. roxburghii seedlings.