The invention relates to a multichannel pulse eddy current online monitoring system, comprising: a PC for setting monitoring device parameters and processing and displaying monitoring data, and a pulse eddy current monitoring device for generating pulse eddy current and collecting pipeline defect data, wherein the PC is wirelessly connected to the pulse eddy current monitoring device. The PC comprises a parameter setting module, a split screen display module and an image synthesis module, and the pulse eddy current monitoring device comprises a pulse eddy current generation module, a power amplifying module, a high speed change-over switch, an array probe, a signal amplifying module, a signal conditioning module and a data collection module, which are electrically connected with each otherthrough conducting wires in sequence. The invention further provides a multichannel pulse eddy current online monitoring method, in which pipeline defect detection is achieved by using pulse eddy current signals. By adopting the multichannel pulse eddy current online monitoring system provided by the invention, real-time monitoring is achieved, and quality or safety problems are discovered, rectified and reformed in the process in time, thereby avoiding personal injury and property loss caused by major quality and safety accidents; and the operation is simple, the implementation is convenient, and the accuracy of the test result is high.