Pestle finger is the enlargement of the end of the finger in the shape of a pestle, also known as mallet finger, and can be seen in a variety of diseases. The human body has three fingers except for the thumb, and the end of the finger referred to by pestle finger is the section of the finger where the nail is long and enlarged. Mallet finger is caused by a disease in the body. Congenital diseases such as tetralogy of Fallot and acquired diseases such as hyperthyroidism, infective endocarditis, and dilated cardiomyopathy can cause pestle finger. The presence of pestle finger symptoms suggests that diseases or lesions of the heart, thyroid, bones and other parts of the body may occur, and it is recommended to go to the hospital in time for examination to clarify the cause of the disease and control the disease as soon as possible, so as to prevent further development of the disease.