Both Mount Aberdeen and Highlander's Bonnet are composed of granite, with Mount Aberdeen summit reaching 901 m and Highlander's Bonnet 624 m. The park is notable for containing the sole regional occurrence of tropical cloud forest at the summit of Mount Aberdeen, with large areas of hoop pine (Araucaria cunninghamii) on the slopes of both peaks.

Semi-evergreen vine thicket (subtropical dry broadleaf forest) is found in sheltered areas.

There is also an unusual red gum-snow grass community in the park that is found nowhere else in Queensland.

Mammals recorded in the park include unadorned rock wallabies, eastern grey kangaroos, common wallaroos, northern quolls and koalas.

Found in the Park is the Mt Elliott grey ant, which is at its southern limit.