This letter investigates a leaky-wave antenna (LWA) utilizing a double-layer offset quasi-complementary (DL-OQC) spoof surface plasmon polaritons (SSPPs) configuration, capable of providing an ultra-high scanning rate within a narrow bandwidth. The top layer of the antenna consists of single-sided grooved SSPPs and single-sided periodically loading stubs. The bottom layer is composed of single-sided periodic slot SSPPs. The top grooves and bottom slots form a DL-OQC structure. The DL-OQC units exhibit strong slow-wave properties, enabling an ultra-high scanning rate. In addition, the asymmetry of the structure helps suppress the open stopband (OSB). The periodically loading stubs on the top layer convert the fundamental mode into a fast-wave region, radiating the electromagnetic (EM) wave into free space. To improve gain and radiation efficiency, semicircular end edges are applied to the loading stubs to generate divergent currents, enhancing surface EM wave disturbance. The proposed LWA was fabricated and meas-ured. The measured results indicate a beam scanning range from ?62° to +30° over the 8.30 ~ 8.62 GHz band, which corresponds to a relative bandwidth (BW) of 3.78%, achieving an ultra-high scanning rate of 24.3°/% BW. The peak gain reaches 11.5 dBi.