Im 20 years old (female) . im not virgin . and everytime when i masturbate some amount of blood came into from my vagina ?

The practice means different things to different folks, and you do not provide any detail about what your activity involves. Bright red blood emerging after any activity implies tissue damage. If yours involves insertion of an object it implies that the affected tissues are injured. The mantra if it hurts when you do that don't do that applies to this practice. An evaluation by your doc is needed.