Provided is an encoder, system and method for metaphor detection in natural language processing. The system comprises an encoding module configured to convert words included in a sentence into BiLSTM representation vectors; a first encoder configured to generate a first entire representation vector of a WSD resolving task; a second encoder configured to generate a second entire representation vector of an MD task; and a multi-task learning module configured to perform knowledge transfer between the first and second encoders. Wherein, each of the first and second encoders includes a graph convolutional neural network (GCN) module configured to encode a link between a target word and a core word to generate GCN representation vectors; a control module configured to regulate the GCN representation vectors to generate an entire representation vector.