Penile shrinkage can be caused by environmental physiological factors, physical obesity, disease factors and other factors. 1. Environmental physiological factors: the environment is too cold, can be due to external environmental stimuli and lead to penile shrinkage, penile corpus cavernosum contraction will be smaller. As men grow older, androgen secretion decreases, which can lead to the physiological phenomenon of penile shrinkage. 2. Physical obesity: after the body becomes obese, due to the thicker subcutaneous fat layer, the volume of the penis is buried in the subcutaneous fat, which leads to the appearance of the penis appears to have shrunken changes. 3. Disease factors: When prostate cancer occurs, the need to apply anti-androgen drug therapy, which can lead to penile shrinkage. Testicular hypogonadism or testicular resection due to disease can also appear after penile shrinkage and decrease in size. When the penis shrinks, you should consult a doctor in time, and under the guidance of a specialized doctor, you should actively carry out the appropriate treatment, which will help to alleviate the uncomfortable symptoms as soon as possible.