One of important equipment in reforestation or tree planting is a pot for mulching tree saplings. Originally pots were made of clay but they were too strong. When the trees grow up the pots must be smashed in order to let the roots and the stems grow up. Plastic pots are a popular alternative to be potted tree saplings due to their longer usability flexibility keeping and easy cleaning. In addition they are light and easy to move or transport. Typical pots usually have holes at the bottom which make poor ventilation that caused the slow tree saplings growth. Pots with holes in the side let the air comfortably flow and the roots do not go to the bottom of the pot. When the pots are moved the tree sapling roots are not ragged this help reducing the mortality rate of tree saplings. To Construct and find out the efficiency of plastic pot injection molded with 7.7 cm. in size 8 cm. high 0.10 cm. thick and the weight of 20 grams in the specification form the work-piece can be injected. For Construction and finding out the efficiency of holes for putting the plastic pot injection molded with 41 cm. wide 51 cm.long0.20 cm. thick and the weight of 330 grams in the specification form every work piece can be injected. There are 18holes for putting the plastic pot and all 18 holes are in the same size. Asst. Prof. Prasong KanKaew