A drug pressuring and delivering system has an internal quantitative pusher for providing stable and precise drug delivery, and a drug pressuring and delivering device for introducing a compression gas for pressuring and ejecting a drug into an atomized drug. The quantitative pusher adopts a bidirectional motor for driving a screw rod to rotate forward or reversely to push the push rod forward or backward, such that the drug is delivered through a solenoid and a drug delivering needle in a cylinder drug delivering pipe and then quantitatively delivered to a drug delivery pressuring tube. In addition, an introduced mainstream gas in the drug delivery pressuring tube forms a gas-liquid mixing and pressuring action to achieve the precisely quantitative and uniform atomization high speed ejection function. Also, all members of the invention can be assembled/disassembled, so that the damaged or contaminated members can be detached, cleaned or replaced.