The invention discloses an insulating oil chromatography analysis full-sealing sample injector which comprises a sample injection head, a sample injection tube and a multi-stage piston structure. The sample injection head is arranged at the lower end of the sample injection tube, a discharge outlet is formed in the upper end of the sample injection tube, the sample injection tube comprises an outer tube and an inner tube, the multi-stage piston structure is arranged in the middle of the inner tube and comprises a piston core rod and a plurality of pistons, the piston core rod comprises a plurality of telescopic rods, the pistons are positioned at the lower ends of the telescopic rods and provided with a plurality of through holes, and valves are arranged in the through holes. The insulating oil chromatography analysis full-sealing sample injector is simple in structure and solves the problems that gas escapes and other gas enters an existing sample injector in the sample injection process or repeated sample injection process. Sample injection precision is improved by a dosing device, and the insulating oil chromatography analysis full-sealing sample injector has the advantages of convenience, rapidness, accuracy and high efficiency.