The work aims to identify and classify different types of plastics, in order to recover plastics that can be used to pack different items. Firstly, the near-infrared spectral data of 16 kinds of plastics including PP, PET, HDPE, TPE, PLA, PBT, TPU, POM-M90, PPO-GF20NC, TPB, PPS, ABS, PPO (natural colour), SAN, POM-F20 and PPO (white colour) were collected. Then, for the problem of noise in spectral data collection, the spectral data were pre-processed by the SG smoothing filtering, followed by dimensionality reduction of the spectral data with the principal component analysis algorithm to reduce the amount of data to be processed, and finally the four-class classification model was established by the K-means algorithm for unsupervised clustering and the great likelihood estimation for supervised clustering, the Fisher discriminant, and the spectral angle algorithm, respectively. The K-means algorithm could distinguish PPO-GF20N, PLA and PPO (native colour) from other plastic particles with an accuracy of 100%, 100%, and 80%, respectively. Fisher's discriminant and great likelihood estimation had an accuracy of 93% for the recognition of POM-M90 and POM-F20, and 100% for the recognition of all other plastic particles. Spectral angle algorithm had a recognition accuracy of 80% for PET, 47% for POM-F20, and an accuracy greater than 90% for the rest of the particles. The above machine learning algorithm combined with near-infrared spectral imaging technology can be used to establish a classification model, providing a reference for the identification research of common plastics.