Abstract: The extreme conditions of the deep-sea zones, such as darkness, high hydrostatic pressure, low temperature (except for black smoker system with hydrothermal activities) and oligotrophication, are factors driving the formation of unique ecosystems. The studies of deep-sea organisms in situ can not only reveal the physiological and metabolic characteristics and dynamic changes of various deep-sea organisms, but also contribute to the development and utilization of deep-sea biological resources. Especially the research on the carbon cycling mechanism mediated by deep-sea microorganisms may provide a new road map for global carbon neutrality. The prior requirement for studying the organisms in deep-sea is to obtain a large number of in situ samples with characteristics well preserved. However, the limitations of traditional deep-sea sampling methods may lead to the morphological and physiological changes of deep-sea organisms, which results in failure in detection of the real in situ life process. Therefore, it is necessary to develop the new sampling methods and optical equipment to satisfy the requirements of the deep-sea biological studies in situ . In this review, we summarize the status and key questions of the deep-sea biology, the progress of deep-sea in situ biological research, the development and application of deep-sea ecological in situ monitoring equipment, and the prospect of deep-sea in situ biological laboratory.