In this paper, five parts of the pseudobulb of P. formosana in the dormant period were used as test materials. The base of pseudobulb, the middle part of pseudobulb, the lateral part of pseudobulb, the junction between pseudobulb and leaf bud, and the junction between pseudobulb and flower bud of pseudobulb were observed and analyzed by means of paraffin section and transmission electron microscopy. The results showed that: (1) vacuoles and vacuolated cells of different degrees were observed in 5 parts of pseudobulb of P. formosa. The epidermal cells were covered with thick waxy layer. (2) There were some chloroplasts in the base, middle and lateral cells of P. formaosa pseudobulbs, and a few mitochondria were distributed around them. (3) Starch grains and powder were found in parenchyma cells of pseudobulbs, and the powder was accompanied by accumulation of starch grains. (4) There were a lot of plasmodesmata between the parenchyma cell wall at the base, middle and lateral of pseudobulb and the junction with flower bud. Plasmodesmata also existed between the sieve tubuleaccessory cell complex and the parenchyma cells, and there were intercellular spaces of different shapes between the cells. The results showed that pseudobulbs of P. formosana played their functions as water storage organs, photosynthetic sites and carbohydrate storage organs, and at the same time, material exchange and transportation were mainly through the symplast pathway during the dormancy period.