The invention discloses a GFP encapsulating method of SONET/ SDH service, which comprises the steps that: a receiving unit of SONET/ SDH service carries out the alignment and frame-fixing operations to the high-speed data code streams at client sides, extracts an SONET/ SDH frame and sends the SONET/ SDH frame to a GFP encapsulating unit; the GFP encapsulating unit divides the SONET/ SDH frame into multi-frame data in sequence and carries out the GFP encapsulation on the multi-frame data obtained by division one frame by one frame; each frame of data is encapsulated into a GFP frame structure; or, the GFP encapsulating unit carries out 64B/ 65B encoding on the SONET/ SDH frame in sequence to obtain a plurality of 65B code blocks; every neighboring 'N' 65B code blocks are combined in sequence to form a SuperBlock; the GFP encapsulation is carried out on each SuperBlock; every SuperBlock is encapsulated into a GFP frame structure. By adopting the method of the invention, the SONET/ SDH service is encapsulated into a GFP frame structure, thus reducing the cost of equipment.