In order to meet the airworthiness requirements and improve the operation performance, there are strict design requirements for the operating handle force of the pressurized cabin door, especially the emergency exit doors. Lifting assist mechanism is the most commonly used lifting auxiliary mechanism on the cabin door, which can effectively adjust the operating handle force of the cabin door. This paper introduces two kinds of typical lifting assist mechanisms of semiplug cabin door for civil aircraft:“spring” and “torsion bar”， and analyzes the mechanism principle. Taking the lifting assist mechanism of a project as an example, this paper analyzes its function in the process of cabin lifting, and the main problems in its application. Based on the above application problems, a new type of lifting assist mechanism for sequence lifting cabin door is introduced, which does not provide assistance when the door is completely closed, and can directly provide larger driving force in the initial stage of lifting. This paper introduces the configuration of the mechanism, analyzes the mechanism principle and working process, and provides a reference for the design of the door lifting assist mechanism and other door mechanisms.