An internal dry powder delivery system through a working channel of an endoscopic cannula for directly applying the powder form medication to an internal tissue/organ site, includes an elongated tubular delivery channel and a powder supply device for producing pressurized gas mixing with the dry powder for feeding to form a mixture of dry powder and pressurized gas delivering to an internal tissue/organ site through the delivery channel via endoscopic cannula. It ensures a smooth powder release by preventing liquid from accumulation at the tip of the delivery channel and offers physicians a new powder form drug delivery method via endoscope. Also, it offers new minimal invasive application by directly and precisely applying the powder format drug to the internal sites of human gastrointestinal organ via endoscope to achieve hemostasis, anti-inflammation, anti-ulcer and anti-tumor treatment, etc.