The invention discloses a processing technology of blast furnace slag powder. The processing technology comprises the following steps of firstly, preliminary screening, secondly, preliminary drying, thirdly, crushing, fourthly, grinding, fifthly, secondary screening, sixthly, secondary drying and seventhly, bagging packaging. In the above first step, a worker shovels out ore slag in a blast furnace, the ore slag is subjected to vibration screening through a mining vibration screen, non-burnt-up ore or large-particle ore slag in the ore slag is filtered to be left above a screen plate, and filtering screening is achieved. In the above second step, the ore slag in the first step is put into an ore slag dryer. By means of the processing technology of the ore slag powder, the ore slag is preliminarily screened before being crushed, non-burnt-up ore existing in the ore slag is recycled, two times of drying treatment are carried out in the early stage and the later stage of the technology, the phenomenon of moisture regain is avoided before production bagging of the ore slag powder, and the finished product quality of the ore slag powder is guaranteed.