The tailbone of the buttocks will be painful when sitting down, mainly because of 2 reasons: 1, it may be the tailbone part suffered trauma, such as suddenly squatting on the ground or suffered external stimulation, the tailbone part has a bone fracture or fracture, so when sitting will lead to the tailbone part of the force, the location of the fracture break is stimulated by friction, and more obvious pain symptoms. The tailbone should be avoided, usually choose one side of the buttocks force, to avoid further stimulation of the tailbone. 2, it may be the tailbone fasciitis, which is due to the tailbone part of the external stimulation, in the case of not fully healed force premature, will lead to the formation of chronic sterile inflammatory lesions, in the sitting position when the fascia is stretched will appear pain, may also be due to the tailbone There are bursae around the tailbone, and these bursae have formed inflammatory edema, which can cause compression of the bursae in the sitting position and also lead to significant pain symptoms.