Safety Insulin Syringe with Restractable Needle Safety Characteristics: after absorbing the expected dose of liquid medicine, if transportation is needed, push up the sliding-sleeve to protect the needle tip from physical damage during transportation; push the sliding sleeve to expose the needle tip before the injection starts, when the expected dose of liquid medicine is 100% injected, manually slide the sliding sleeve to the position where the connector base can no longer slide, the needle tip is completely covered in the sliding sleeve, and then the sliding sleeve is manually rotated until it is locked, it could effectively preventing repeated use and accidental needle sticking, and avoiding cross infection.