In recent years, microscopic imaging technology is playing an increasingly important role in neurobiology, cell biology and microbiology. On the basis of high spatial resolution, if the field of view (FOV) is greatly improved and the time bandwidth is saved, microscopic imaging will play an important role in the research of the mechanism of neural circuit connection, increase imaging flux and provide the possibility for the digital storage of generous samples. Scanning imaging is now one of the major ways to increase FOV. However, the time bandwidth of traditional "walk-stop-shot" scanning mode is limited to the time-consuming signal transmission among the host computer, the host computer and the camera. This paper presents a microscopic imaging system for slice scanning by a distinctive "continuous scanning imaging mode", the camera exposures under continuous scanning motion. Based on FPGA, the location is obtained from the real-time decoding of the gratings signal, and the TTL signal controlling the camera is generated by the position comparator. And, 1) a pre-calibration strategy is adopted to ensure each sub FOV is within the depth of field, 2) a PID control algorithm based on piecewise interpolation is proposed to optimize the motion performance of the sample platform, 3) a fast iterative image restoration algorithm based on maximum a posteriori estimation is established to remove motion blur from a single image under high speed scanning motion. Finally, a 20mm x 15mm FOV (21722 x 17474 pixels) is scanned under the 20 times high NA objective lens less than 60s.