With the development of modern industry, it can be said that from industrial production to the basic necessities of life, plastic products can be seen everywhere. What follows is the disposal of plastic waste. How to deal with plastic waste correctly is closely related to people's health and the earth's environment. In this paper, laser-induced breakdown spectroscopy is applied for the online in situ detection of plastic and its combustion smoke. According to the spectrum obtained, the main components of plastics are Ca, Mg, Na, K, C, H and O. In the spectrum of smoke, the characteristic peaks of the elements C, H, O and N are observed. In addition, the online detection of heavy metal pollution is simulated. Finally, principal component analysis and error back propagation artificial neural networks were applied for the identification of different plastics and their combustion smoke, and the identification accuracy reaches 92.73% and 77.42% respectively. All the results indicate that laser-induced breakdown spectroscopy technology has great potential in the identification of similar objects and the monitoring of air pollutants.