The invention discloses an on-line lithium battery pole piece surface defect detection sorting system and method. The synchronous real-time on-line detection on positive and reverse sides of pole pieces is realized through a pole piece conveying device, a pole piece identification and detection part, a pole piece master control unit, a pole piece sorting device and a human machine interface part; a mechanical structure of the system is simple, the detection on the positive and reverse sides of the pole pieces can be realized in the system through a simple detection channel, and the system is simple, feasible and low in cost. The detection speed is high, the general detection speed is superior to 2 pieces per second, the detection precision is high, and an embedded visual identification detection technology adopted by the system has the high precision with the omission ratio of 0 and the error detection rate of less than 2 percent. According to the pole piece detection sorting device, the secondary damage of the pole pieces is avoided. The actionability is high, and the system is long in operating time, can operate for long time in the industrial field and has the advantages of convenience in maintenance, high portability and the like.