Endothelium of Blood - The inner endothelium of blood is smooth
and negatively charged.This prevents the platelets plug to stick
with the surface of blood vessels and prevents the blood clot
formation.
Anticoagulants - Many natural anticoagulants are present in our
body which prevents the formation of clot .
Blood circulation - The blood circulates continously, due to
the velocity of blood flow it prevents the formation of blood clot
normally.