Introduction: Ferns (Pteridophyta) are plant communities that have an ecological function as ground cover vegetation. The purpose of this research types of ferns (Pteridophyta) and the diversity index of ferns found in the Batang Gadis National Park Resort 7 Sopotinjak, Batang Natal Sub-district, Mandailing Natal District, North Sumatra Province. Materials and Methods: Descriptive survey method using quadratic plot of 24 plots in three transects. Results: It was found that five from 28 species of dominant fern were: Asplenium nidus, Asplenium normale, Shaeropteris glauca, Oleandra undulate, and Asplenium lobulatum. The diversity index of ferns (Pteridophyta) of 2.494 and was categorized as moderate, which means that the ferns (Pteridophyta) are stable, this indicates that the ecosystem is in a fairly balanced state.