The invention discloses an inner shot blasting device and method for a steel pipe. The inner shot blasting device and method for the steel pipe overcome the defects of time and force wasting low efficiency and poor shot blasting effect due to manually handholding a blasting gun for blasting in a steel pipe in prior art. According to the technical scheme, the device is characterized in that a sandblasting adapter which can be driven to rotate around own axis through a driving assembly is arranged at the front end of a pushing moving trolley, wherein the sand blasting assembly comprises an inclined sand blasting pipe; one end of the sand blasting pipe communicates with the sand blasting adapter while the other end of the sand blasting pipe is provided with a sand blasting head; the sand blasting head is forwards arranged and faces the inner wall of the steel pipe; the sand blasting adapter is rotated to drive the sand blasting pipet to move in the steel pipe as well as drive the sand blasting head to move in a circular route; a pneumatic shot conveying assembly comprises a compressed air pump and a conveying pipeline; and the conveying pipeline communicates with the compressed air pump, thus compressed air is used for driving sand for shot blasting to be conveyed from a sand container to the sand blasting adapter and the sand blasting pipe and then discharging through the sand blasting head. The device has the advantages that the sand blasting and shot blasting efficiency is high; and the shot blasting effect is good.