Stroke often causes motor dysfunction of the knee joint. Existing rehabilitation equipment lacks customization, limiting training effectiveness. This paper presents a soft pneumatic exosuit (SPE) designed to provide effective and comfortable daily knee rehabilitation training for stroke patients. The SPE features a wearable sleeve with anterior and posterior airbag drive units (AP-ADU) for bidirectional actuation. Weighing only 210 g, it is lightweight and compliant. A multi-bag array structure improves actuation performance. Each airbag is made of a double-layer thermoplastic polyurethane (TPU) laminated to a mesh fabric composite and curved to better fit the lower extremity. Finite element analysis (FEA) was first used to assess structural performance. Subsequently, the SPE was verified by surface electromyography (sEMG) experiments. The results showed that root mean square (RMS) peak values of the target muscle groups activation respectively decreased by 20.7%, 6.5%, and 12.7% during knee extension, flexion, and squatting, demonstrating the effectiveness of the exosuit and the potential for rehabilitation.