In order to provide effective communication link between two robots while physical link did not exist in unknown environments, a method of active communication link building on demand was proposed. Based on some model assumptions and definitions, a strategy named SSS was presented to build communication link in unknown environment by using link-increasing and link-rotating. Then the corresponding basic algorithm and improved algorithm were discussed and compared in simulation. The simulation indicated that communication link could be built successfully by employing these algorithms. And the improved algorithm had more optimal performances than basic one by estimating energy consumption and time consumption in link building process.