Volatile organic compounds (VOCs) are not only harmful to human health, but also important precursors of ozone and PM_2.5, which cause severe air pollution. Therefore, it is critical to study these compounds, and monitor them by developing reliable and effective techniques. Passive air samplers (PASs) are small and uncomplicated, with the advantages of simple operation, easy transportation, and do not require external power; therefore, they are more economical and practical to monitor VOCs compared to active sampling techniques. As an alternative method, passive sampling is particularly suitable for long-term monitoring in remote regions and wilderness areas, simultaneous large-scale measurement, and recording of individual exposure. In recent years, commercial PASs have been improved continuously, while emerging samplers have been developed for new applications. The following main trends can be distinguished: (1) many novel PASs were specifically designed to monitor only one or few VOCs also including numerous redesigned commercial PASs; (2) the improvement of sorbents is still ongoing towards high efficiency, low cost, and multiple choices for more analytes; (3) structural improvement is another important aspect of PAS development mainly focusing on both sampler performances and applications; (4) the development of new technologies provides more sampling conveniences such as using unmanned aerial vehicles and sampling robots to special monitoring sites e.g., a stack or a ventilating duct.