Microlaryngoscopic surgery is a type of laryngeal surgery performed by surgeons using microsurgical instruments under the observation of a specially designed laryngoscope. While performing a microlaryngoscopic operation, the surgeons must maintain their arms' position for a long time, which can cause arms' soreness and affect the accuracy of the operation. In this study, a tendon-sheath-driven upper limb auxiliary exoskeleton (TULAE) is proposed and developed. The flexible cables are compressed by a wave-shaped pressing mechanism to fix the TULAE's rotating joints. The TULAE can assist surgeons in laryngoscopy operations by providing suitable support for their arms to reduce the surgical risks caused by muscle fatigue. The TULAE has four degrees-of-freedom (DOFs) on each arm. The shoulder flexion/extension, shoulder abduction/adduction, and elbow internal rotation/external rotation can be fixed by the control box. The shoulder internal rotation/external rotation is a passive DOF obtained using hinges. The TULAE's shoulder, upper arm and forearm links are designed with lengths adjustable to accommodate wearers of different heights and weights. A large-scale but risk-free workspace is analyzed through rigid body kinematics using the spinor method. The control hardware of the TULAE is developed based on the open-source Arduino board. Finally, the experimental results show that this TULAE can significantly reduce the range of wrists shaking and assist surgeons in laryngoscopy surgery.