The invention discloses a high-
voltage cable on-line monitoring method and device, and relates to the technical field of on-line monitoring. The method comprises the following steps: after a high-
voltage cable insulating layer is extruded, acquiring and
processing electric field intensity data to obtain processed data; constructing an ideal
electric field distribution
reference model, comparing the processed data to calculate an
electric field matching root-mean-
square error, and if the error exceeds a first threshold value, performing early warning and marking an insulation abnormal area; detecting after the shielding layer is formed to obtain excitation end input power and receiving end output power, calculating
electromagnetic signal power attenuation, and marking a shielding layer defect area if the
electromagnetic signal power attenuation exceeds a second threshold value; calculating a spatial
cross validation index according to the error and the attenuation amount, and marking a cross defect area if the spatial
cross validation index exceeds a third threshold value; and constructing a defect evolution trend probabilistic model, inputting a real-
time error, an attenuation amount and a
cross validation index, outputting a defect deterioration
posterior probability, and carrying out graded early warning. According to the method, defects of all links of production are covered through full-process real-time monitoring, and the limitation that traditional sampling detection cannot cover production batches is changed.