To address the practical requirements of daily activities, this research proposes an underactuated humanoid dexterous hand designed for multi-finger adaptive synergic grasping. This anthropomorphic hand incorporates a wheel chute actuating mechanism and an interfinger differential mechanism to enhance functionality. The compliant joints of the dexterous hand facilitate the adaptivity of grasping objects with diverse shapes. A spatial kinematic model of the robotic joints is developed based on the geometric configuration and static analysis of the dexterous hand. Additionally, the workspace and the trajectories of the fingertips are analyzed. An experimental platform has been established for conducting PID control experiments and evaluating the grasping capabilities using fingertip pressure measurements. The results reveal that the proposed underactuated humanoid dexterous hand can reliably grasp a wide range of daily necessities with a grasp weight ratio of up to 1.43, demonstrating its substantial practical utility.