In the process of the wire and plasma arc additive manufacturing,due to the accumulation of heat in the heating process,the difference between the height of the actual compress layer and the designed compress layer makes the arc length difficult to be constant;at the same time,the change of process parameters will also affect the stability of the additive manufacturing process.Therefore,the intelligent prediction for arc length and monitoring system based on LabVIEW is designed for wire and plasma arc additive manufacturing process.The system takes the USB4711 A acquisition card as the core,and uses sensors to collect signals such as current and voltage on the wire and plasma arc additive manufacturing process,and displays real-time process parameters,process information and data analysis.Meanwhile,an intelligent prediction model of arc length based on BP neural network is established to monitor the change of arc length in the process of additive manufacturing.The experiments show that the process monitoring system can monitor the process of additive manufacturing process in real time.By real-time invoking the BP neural network of 3-7-1 structure,it can predict the change of the arc length in real time,and the error range of the prediction is from-1.6 mm to 1.4 mm,reaching the expected requirement.