There are two pronunciations of blood: blood (xuè) and blood (xiě).

whenever "blood" is used as a morpheme to form a disyllabic word or a polysyllabic idiom, we should all read xuè. The former is like blood, blood color, bloodshot blood and veins, while the latter is like flesh-and-blood connection, maw of blood, gore of flesh and blood, and blood shed (note: the idiom "hit the nail on the head" may be because it comes from the common spoken language).

if "blood" is used alone, read xiě, such as "blood all over the floor" and "bloody face". That is to say, read xuè in written language and xiě in spoken language. There is a typical example: "blood debt should be paid with blood." According to the pronunciation method above, the former "blood" is a morpheme, pronounced xuè, and the latter "blood" is a separate word, pronounced xiě.

Extended information:

Blood (pinyin: xuè, xiě) is a common Chinese character, and its earliest glyph was found in Oracle Bone Inscriptions in Shang Dynasty. In ancient Chinese characters, blood is like the blood of livestock in a sacrificial vessel. It originally refers to the blood of livestock offered to the gods during sacrifice, and later refers to the blood of people and animals. Blood is extended from blood to having the same ancestor, and it is also a metaphor for being strong and warm.

Explanation of the etymology of blood:

The word "blood" first appeared in Shang Dynasty, and the lower part was a vessel with a seat, like a small dish; There is a small circle in the "dish" shape, indicating blood drops. "dish" is a foil condition, which not only shows the liquid state of blood, but also shows that it can be filled with sacrifices. Later, the small circle was reduced to a short vertical.

In the Western Zhou Dynasty, the short vertical became short horizontal, indicating that most of the arc lines of the vessels no longer extended upward, but became shallow arcs that tended to be low and flat. Between the two vertical lines of the holder, or add one or two horizontal paintings as ornaments; The seal script basically follows the bronze inscription of the Western Zhou Dynasty; Into the Han dynasty, short and long; By the Eastern Han Dynasty, the elongated horizontal line began to change from high to the right and low to the left, and developed into the upper left in regular script. The lower folding lines at both ends of the vessel collided with the bottom horizontal line, which was inherited by regular script after the Han Dynasty.

Reference: Baidu Encyclopedia-Blood.