Tracking　a　specified　target　is　a　fundamental　task　of　service　robots.　This　paper　studies　and　designs　a　monocular　mobile　robot　tracking　system　based　on　Fully-Convolutional　Siamese　Networks.　This　tracking　mobile　robot　system　uses　the　Siamese　convolution　network　as　the　tracker　to　lock　the　target.　The　bearing　conversion　algorithm　and　speed　conversion　algorithm　are　combined　to　implement　following　the　target　stably　and　accurately.　The　bearing　conversion　algorithm　keeps　the　tracking　target　in　the　middle　of　the　image　and　calculates　the　moving　angle　according　to　the　distance　from　the　center.　The　speed　conversion　algorithm　sets　different　speeds　according　to　the　ratio　of　bounding　box　area.　Implementation　of　the　monocular　mobile　robot　tracking　system　is　grounded　on　the　Robotic　Operating　System　(ROS)　platform.　The　experiment　shows　the　effectiveness　of　the　implemented　the　monocular　robot　tracking　system　which　can　achieve　real-time　following　target　at　variable　speeds　according　to　the　forward　speed　of　the　tracking　target　with　safety　distance　even　though　having　occlusion.