During the drilling process, if a high-pressure gas layer is encountered during drilling, gas kick may occur. In the initial stage of gas kick, it is difficult to accurately detect it through methods or equipment such as pit liquid level detection and flow difference overflow detection. Moreover, as the well depth increases, the difficulty of detecting gas kick in advance increases, and the reaction time left for well control is significantly reduced, making early detection of gas kick a key and difficult point in deep well control. For deepwater drilling, firstly, as the water depth increases, the safety density window narrows, making it more prone to gas kick; Secondly, due to the presence of deep water and high static pressure environments, the overall scale of bubbles reaching the seabed wellhead is still relatively small, resulting in the possibility that the increment of the pit on the sea surface may not reach the warning value when gas enters the riser, making it difficult to detect gas kick in a timely manner through conventional methods. Therefore, the risk of gas kick and well control in deepwater drilling has significantly increased compared to shallow sea drilling. How to timely and accurately detect gas kick and ensure well killing safety has become the top priority of deepwater drilling well control work. On the basis of introducing the calculation model of wellbore annular pressure during gas kick in deepwater drilling, this chapter analyzes the factors that have a significant and uncertain impact on the safety of gas kick and well killing by calculating the risk of well killing under different factor conditions, and establishes a quantitative calculation method for uncertain factors; At the same time, calculate the impact of different factors on gas kick in deepwater drilling, analyze the relationship between the location of gas kick (cross-sectional gas content) and overflow flow (pit increment), explore new ideas for early monitoring of gas kick in deepwater drilling, in order to accurately detect gas kick in advance and quantitatively describe the degree of gas kick.