The invention discloses a detection apparatus and detection method for hydrogen cyanide in a research lab. The detection apparatus comprises a controller, a memory, a base plate, a rectangular cross section equipped air chamber and a support frame arranged on the base plate, and a guide structure and a cross lead screw arranged on the support frame. The inner wall top of the air chamber is provided with an ultrasonic generator and several fans for blowing down, the inner side wall of the air chamber is equipped with a gas sensitive film, a metal net composed by heating wires and for supporting the gas sensitive film, a horizontal separator plate that is located below the metal net and separating the inside of the air chamber into an upper part and a lower part from top down in order, and the air chamber is internally provided with an ultrasonic receiver, a support plate, a detection head and a track spirally distributed along the upper surface of the support plate. The detection apparatus provided by the invention has the characteristics of high sensitivity, good stability and short response time, good selectivity to hydrogen cyanide, and ability to detect lower concentration trace hydrogen cyanide gas, thus effectively guaranteeing people good health.