To realize the demand of processing the air film hole of aviation turbine blade without metamorphic layer, the EDM–drilling combined machining system was developed. According to the demand of the system mentioned above, to work and control in coordination with two axes, system architecture needed to be designed and optimized, which ensures that EDM and drilling operate independently of each other. Meanwhile, the system can realize automatic control of motor spindle speed and the stepless adjustment of feed rate. Based on the combined machining system, a processing technology of micro-hole composite without metamorphic layer was developed. During the processing, firstly, a micro-hole was processed by EDM. In order to removal the metamorphic layer on the hole wall completely, where the hole needed reaming with drilling tool. The basis of the technology mentioned above, a series of compound processing experiments of straight hole and 20° inclined hole were carried out. The tolerance range is (0.315±0.003) mm. The experimental results show that the EDM–drilling composite machining has the advantages of high machining efficiency, high hole shape accuracy and no metamorphic layer on the hole wall.