The installation hole of a certain type of integrated processing spacecraft product is located in the interior of the cabin body,and the upper part has feature interference,the conventional processing method cannot realize the processing of this part.Aiming at the problem， by analyzing the structure characteristics of right-angle milling head,the tool point compensation algorithm of HNC system was studied,and the bidirectional compensation between the machine tool controller and the tool point of right-angle milling head was realized.Combined with the structure of Longmen five-axis machine tool and the characteristics of coordinate system transformation,the post-processing development was carried out based on NX,the post-processing file development was completed based on the coordinate system compensation of right-angle milling head,and the automatic output of the compensation program was realized in the event form without changing the original post-processing.The installation hole processing of the ultra-thin cabin body small parts was successfully solved,the applicability of HNC system gantry five-axis machine tool was improved.