PA 274 begins at an intersection with PA 75 in the community of Doylesburg in Fannett Township, Franklin County, heading northeast on two-lane undivided Big Spring Road. The road heads through a mix of farmland and woodland with some homes before ascending forested Conococheague Mountain. The route heads into the Tuscarora State Forest and enters Toboyne Township in Perry County and becomes an unnamed road, making a hairpin turn to the southwest before another hairpin turn to the northeast to descend the mountain, passing by Big Spring State Forest Picnic Area. PA 274 runs through more of Tuscarora State Forest before leaving the forest boundaries and heading into open agricultural areas with some homes, passing through New Germantown. The road enters Jackson Township and becomes Mt. Pleasant Road, coming to Mt. Pleasant and becoming an unnamed road again. The route heads into the borough of Blain and passes homes, reaching an intersection with PA 17 and turns southeast onto Main Street. PA 274 curves to the east and heads back into Jackson Township, turning northeast into more open farmland as an unnamed road. The road crosses into Southwest Madison Township and curves more to the east, running through Andersonburg. The route heads through more rural areas and passes through Cisna Run and Centar. PA 274 heads through farmland with some woods to the south as it continues into Northeast Madison Township and intersects PA 850 in Fort Robinson.