The invention discloses a method for detecting the habitat fitness of insects by using an arginine kinase gene. The invention discloses an application of any product shown in (1)-(6) in the specification to identification or auxiliary identification of the habitat fitness of insects. The time of 2-3 days is only needed to detect the habitat fitness of insects by adopting a primer pair and method provided by the invention but the time of about 30-60 days is needed by adopting traditional biological methods. The detection method provided by the invention has the beneficial effects that the materials used in the method are wide in sources and are easy to purchase; the method is simple to operate, saves time and labor and is suitable to popularize and apply in insect commodity inspection and detection.