Abstract:A Comparative anatomical structure observation on Brassica chinensis L. plants under solution culture with various phosphorus and potassium concentration were made by optical microscope and SEM. The results showed that the effects on the plants under different phosphorus and potassium levels appeared in the development of cuticle, the number of chloroplast in mesaphyll cell, the activity of vascular cambium cell and the amount of root hairs etc. In addition, the effect of low-K to the open of stomata was found. Phosphorus and potassium under the balanced nutrition make cells differentiation well and yield great or else unfavourable.