The invention discloses an OCT (Optical Coherence Tomography) system for measuring the optical path value of an axis oculi and a method. The system comprises an OCT system light source, an optical fiber coupler, a detection system, a control system, a sample arm component, a reference arm component, a cornea before-and-back position alignment component and an outer eye camera component, wherein the outer eye camera component is used for monitoring an iris of eyes under test, and an operator controls the sample arm component to adjust a corneal vertex to the main optical axis of the OCT system according to the iris; the control system is used for judging the distance from the corneal vertex to an eye objective lens, and the distance from the corneal vertex to the eye objective lens is adjusted to meet the requirement on work of the system by means of the before-and-back adjustment of the sample arm component controlled by the control system; an optical path adjusting component adjusts the optical path of the sample arm component, and thus fundi of different human eyes are matched with the optical path of a reflector of a reference arm of the system to realize the OCT imaging of the fundi; the optical path value LEye of the axis oculi of the human eye can be measured according to the formula: LEye=LRDK1toEc+S+hRetinal. According to the OCT system for measuring the optical path value of the axis oculi and the method, the corneal vertex is accurately positioned, and by combining with the fundus OCT imaging technology, the test result of the optical path value of the axis oculi of the human eye is more accurate.