A tendo calcaneus suturing instrument, comprising: a first support (10) and a second support (20) that are of a U-shaped structure, a distance adjustment device (3), a first guide sleeve (13), a second guide sleeve (23), a first positioning tube (14), a second positioning tube (14) and a tendo sheath cutter (4). An outer arm and an inner arm of the first support (10), and an outer arm and an inner arm of the second support (20) are respectively provided with a first positioning hole (11), a first guide hole (12), a second positioning hole (21) and a second guide hole (22) and the first guide sleeve (13)/the second guide sleeve (23)is fixed by means of the first positioning hole (11)/the second positioning hole (21) and is matched with the first guide hole (12)/the second guide hole (22). The first positioning tube (14)/the second positioning tube (14) provided with a through hole is arranged in the first guide sleeve (13)/the second positioning sleeve (14) or the tendo sheath cutter (4) is arranged in the first guide sleeve (13) and/or the second guide sleeve (23) in a matching manner. The tendo calcaneus suturing instrument can simplify the surgical procedure, improve the surgical effect and relieve pains of a patient.