Nowadays, bending workpiece angle measurement methods require touching the surface, which makes them prone to scratching the workpieces and inefficient. To solve the above problems, we propose a non-contact angle measurement system based on multi-line structured light. First, a bilinear laser is projected onto the surface of the workpiece and the machine tool lower die. However, reflections on the smooth workpiece will greatly destroy measurement accuracy. In this work, a UNet-based multi-exposure image fusion strategy is proposed to clip the reflection and increase the workpiece feature. Then, the Steger algorithm is used to achieve high-precision localization of the laser centerline. Finally, the angle of the workpiece is calculated indirectly according to fitting the laser centerline plane. The experimental results demonstrate that the measurement time of each workpiece is less than 100 ms and the measurement accuracy is ±0.3 deg in extreme installation locations and shadow. The proposed system can be extended to real industrial scenarios because of its high efficiency, accuracy, and robustness.