The invention discloses a construction method of three parallel metro tunnels with an ultra-small clear distance. The method includes a tunnel portal and open-cut tunnel construction method, a barrel digging method, an explosion method, an advanced small pipe construction method, a steel mesh hanging method, a vertical steel frame erecting method, a combined anchor rod construction method, a primary lining supporting construction method, a tunnel waterproof construction method, a secondary tunnel lining construction method, a pouring method, a geological advanced forecast method and a monitoring and measuring method. Compared with the prior art, the construction method is advanced, reasonable, efficient and concise; on the basis that stability of surrounding rocks, constructed tunnels and surrounding buildings and safety of construction personnel in a construction area are guaranteed, engineering quality is guaranteed, construction cost is effectively lowered, the constriction time is shortened, and social benefits and economic benefits of enterprises are remarkable.