The arches resist general loading by a combination of axial compression and bending actions which vary along the arch. Under these actions, an arch may suddenly deflect laterally and twist out of the plane of loading and fail in a lateral-torsional buckling mode. This paper investigates the lateral buckling strength and design of steel arches under general loading. It is found that the subtended angle and load distribution significantly affect the lateral buckling strength of a steel arch. The rules for designing steel beam-columns against lateral buckling cannot be used directly in the design of steel arches against lateral buckling under general loading, because they do not include the effects of the subtended angle. The buckling loads of arch with different load condition, subtended angle, manner of laying section are calculated by finite element method. The interaction equation against lateral-torsional buckling for steel arches subjected to combination of bending and axial compressive actions is proposed. The safety and applicability of the interaction equation is verified by parameter analysis.