Abstract: ObjectiveThis experiment analyzed the influence of different combination ratios of nitrogen,phosphorus and potassium on growing Dendrobium officinale tissue culture plantlets,in order to provide reference for tissue culture and rapid propagation, as well as management of field fertilization. MethodTissue culture plantlets of D. officinale at strong-seedling stage were used as experimental materials. Effects of different combination ratios of nitrogen, phosphorus and potassium in media on plant height, leaf number, new root number, tiller number, relative weight gain rate were studied by means of L9(33) orthogonal design method. Single factor experiments with multiple levels on potassium which had signifi-cant effects were carried out. ResultRange analysis results showed:nitrogen was the biggest factor affecting plant height and tiller number; potassium had the largest impact on new root number and the relative weight gain rate; phosphorus in-fluenced leaf number the most. Variance analysis results indicated that:amount of nitrogen,phosphorus and potassium had no significant influence on leaf number and new root number (P>0.05); nitrogen level had obvious impact on plant height and tiller number,and the plantlets grew in N2(nitrogen 30.0 mmol/L) were the highest, plantlets in N3(nitrogen 60.0 mmol/L) had the largest tiller number. Potassium level had significant impact on relative weight gain rate (P<0.05) and the plantlets grew in K3(potassium 20.0 mmol/L) gained the largest relative weight gain rate. Potassium ion con-centration experiment showed that, within a certain range, relative weight gain rate increased as potassium ion concentra-tion rised, and relative weight gain rate of the plantlets increased and the ones in k5(potassium 40.0 mmol/L) was the largest. ConclusionFor D. officinale tissue culture plantlets at proliferation stage, the optimal concentrations of nitrogen, phosphorus and potassium were 60.0,1.2 and 20.0 mmol/L,at strong-seedling stage, the most appropriate concentrations were 30.0,1.2 and 20.0 mmol/L. Moreover, in the process of seedling culture,plant growth regulators,organic and inorganic nutrients can be added into the media on this basis.