The reasons for bleeding when constipated are as follows: 1. Because of constipation, defecation is more laborious and laborious, so the constipated fecal mass stimulates the rectal mucosa, which can easily lead to the rupture of the local mucosa, so it is easy to bleed. 2. Long-term repeated constipation may cause the local rectal mucosa to occur anal fissure, small fissures appear, so when constipation is more serious, the anal fissure rupture bleeds again, this situation is more common in the clinic. 3, due to internal hemorrhoids nucleus prolapse, constipation may defecate hard, will lead to bleeding hemorrhoids nucleus, this situation of internal hemorrhoids patients have a higher chance of occurrence, the discharge of fresh blood and feces do not mix together. In conclusion, constipation and bleeding must be specifically found in the hospital to find the cause, and then systematic and standardized treatment according to the cause.