A disposable pre-filled syringe has a protecting tube, a medication filling tube, a separating plug, a pushing module, and a needle module. The medication filling tube is made of chemically inert material and is mounted in the protecting tube. The separating plug is mounted in an end of the medication filling tube. The pushing module is slidably inserted into the medication filling tube opposite to the separating plug. The needle module is mounted on an end of the protecting tube.