本发明涉及一种大丝束PAN基碳纤维原丝的上油方法,主要解决现有技术中存在采用碳纤维原丝用油剂中乳化剂用量大,造成油剂在使用过程中耐热性差的问题。本发明通过采用:一种大丝束PAN基碳纤维原丝的上油方法,在30~50℃和常压条件下,将质量分数0.5%~3.0%油剂乳液浸渍经致密化后丝束>24k的PAN基碳纤维原丝, The invention mainly relates to a method for oiling a large tow PAN-based carbon fiber precursor yarn, which mainly solves the problems that the use amount of the emulsifier in the oil agent for using the carbon fiber precursor fiber is large in the prior art, causing the oil agent to have poor heat resistance during use . The method comprises the following steps of: using a method for oiling a large tow PAN-based carbon fiber precursor yarn, impregnating the oil emulsion with the mass fraction of 0.5% to 3.0% under the condition of 30 to 50 DEG C and normal pressure, 24k PAN-based carbon fiber precursor,