The disclosure provides an intelligent method and system for monitoring pig behavior abnormality. The method comprises: acquiring an instantaneous acceleration of a pig; calculating an instantaneous acceleration variation according to the instantaneous acceleration; calculating a sampling characteristic value according to the instantaneous acceleration and the instantaneous acceleration variation; calculating a threshold according to historical data; drawing a box diagram according to the sampling characteristic value and the threshold; judging whether the sampling characteristic value exceeds the threshold according to the box diagram; if not, reacquiring the instantaneous acceleration of the pig and calculate the instantaneous acceleration variation; and if so, sending an alarm signal. An alarm signal is sent out after an abnormal behavior is detected by comparing the sampling characteristic value and the threshold, so that the abnormal behavior of the pig can be found in time, and the feeding safety is improved.