1. Wipe off the blood stain. Place a towel directly under the stain on your pants. Use a clean cloth soaked in cold water to soak up the excess blood. Do not rub the stain，Rubbing will cause the stain to spread. Do not use warm or hot water either. Hot or lukewarm water will cause the stain to clot.
2. Soak the pants in cold water. 20 to 30 minutes and then remove the pants from the water. Remove the blood stain with salt and soap, rub, wash, and wring the pants by hand or put them in the spin cycle of the washing machine.