Environment quality decrease is one of the impact of coal mining activities in East Kalimantan. The land becomes barren and critical, making it difficult for plants to grow and adapt, therefore post-mining area needs to be rehabilitated to restore the soil of the land as an important factor in crop cultivation. Before being planted with local trees, the environmental conditions must be suitable for seedlings to be planted. One of the pioneer plants functions is to stabilize the post-mining environmental conditions. The objective of this study was to determine a pioneer species that have a well adapt to the post-coal mining environment in East Kalimantan. This study using completely randomized block design. The plot used a rectangular 30×25 meter plot of 15 plots for five pioneer tree species. Data collected were the plant life percentage, plant height, stem diameter and crown diameter. The study result showed that from the five species of pioneer plants there were three species has an optimal growth they are Alstonia scholaris, Homalanthus populneus and Croton argyratus. Based on the List Significance Difference test 5% level results shows the Alstonia scholaris and Croton argyratus life percentage is not significantly different with Homalanthus populneus, but it is very different from Macaranga gigantea and Trema tomentosa. Homalanthus populneus is the most adaptable pioneer species in the open area, its growing in the open post-mining area and from the forest with has intact condition. The genetic factors really affect the adaptation and growth of pioneer plants in post-mining areas.