Taking 42CrMo high-strength steel,which is difficult to be processed,as the research object,an experimental study on BTA deep-hole drilling of 42CrMo high-strength steel was carried out to solve the problems such as the difficulty of chips cutting in the deep hole drilling.In order to obtain the ideal chip shape,the influence law of spindle speed and feed rate of BTA deep hole drilling machine tool on chip shape was analyzed.The experimental results show that when the rotational speed is 195 r/min and the feed rate is 0.18 mm/r,the chip presents the ideal C-shaped chip and short roll chip,and the tool wear is relatively minimum,which is conducive to the smooth chip discharge and stable machining process.