Abstract: This study aimed at the problem of difficulty in autonomous dressing caused by the decline of physiological functions in the elderly group and designed and developed a modular clothing assistance wearable device.Based on the principles of ergonomics,a parametric three-dimensional model was constructed, and a collaborative mechanical system including three functional modules: coat assistance, inner lining positioning,and trouser suit lifting was innovatively developed. Static simulation analysis was carried out through the ANSYS Workbench platform. With the optimization goals of improving the load-bearing capacity of the device, reducing the deformation and enhancing the degree of automation, the functions were optimized specifically and the goals were achieved. Finally, finite element simulation calculation and fatigue analysis were carried out on the optimized mechanical structure to verify its safety and reliability. The research results show that when the lifting platform structure bears a horizontal load of 2000 N, the total deformation is only 0.5 mm. The hydraulic mechanical arm can complete approximately 1.2×10⁴ cycles under repeated bending at periodic bending moments, meeting all mechanical conditions and design requirements, and can provide a theoretical reference for the research of elderly care fitting devices.