A sample staining device, comprising: a staining platform provided with a staining liquid supplying portion, a cleaning liquid supplying portion, and a liquid supplying groove on a surface thereof, wherein the liquid supplying groove is provided with a liquid outlet configured to supply a working liquid to the staining platform, and both ends of the liquid supplying groove extend to the edges of a slide supporting structure; a slide supporting structure located on both sides of the staining platform and configured to form a gap between a slide and a surface of the staining platform; a slide driving mechanism configured to move the slide with respect to the staining platform, maintaining a clearance movement of the slide with respect to the length direction of the staining platform; and a working liquid supplement groove in communication with a liquid outlet provided in front of the liquid supplying groove along the passing direction of the slide, characterized in that the working liquid supplement groove extends from an edge of the slide supporting structure and ends at a centre line of the staining platform that extends along the passing direction of the slide, both the liquid outlet of the liquid supplying groove and the liquid outlet of the working liquid supplement groove are located at the centre line of the staining platform that extends along the passing direction of the slide; and wherein the staining platform is provided with an overflow groove on a periphery thereof which is disposed parallel to the edges of the slide supporting structure and at a position where a staining area and a cleaning area meet the slide supporting structure, and the overflow groove is configured to discharge an excessive amount of the staining liquid or the cleaning liquid to prevent the liquid from overflowing the staining platform. a staining platform provided with a staining liquid supplying portion, a cleaning liquid supplying portion, and a liquid supplying groove on a surface thereof, wherein the liquid supplying groove is provided with a liquid outlet configured to supply a working liquid to the staining platform, and both ends of the liquid supplying groove extend to the edges of a slide supporting structure; a slide supporting structure located on both sides of the staining platform and configured to form a gap between a slide and a surface of the staining platform; a slide driving mechanism configured to move the slide with respect to the staining platform, maintaining a clearance movement of the slide with respect to the length direction of the staining platform; and a working liquid supplement groove in communication with a liquid outlet provided in front of the liquid supplying groove along the passing direction of the slide, characterized in that the working liquid supplement groove extends from an edge of the slide supporting structure and ends at a centre line of the staining platform that extends along the passing direction of the slide, both the liquid outlet of the liquid supplying groove and the liquid outlet of the working liquid supplement groove are located at the centre line of the staining platform that extends along the passing direction of the slide; and wherein the staining platform is provided with an overflow groove on a periphery thereof which is disposed parallel to the edges of the slide supporting structure and at a position where a staining area and a cleaning area meet the slide supporting structure, and the overflow groove is configured to discharge an excessive amount of the staining liquid or the cleaning liquid to prevent the liquid from overflowing the staining platform.