The invention provides a method for preparing a humidity-sensitive switch flexible sensing material. The method for preparing the humidity-sensitive switch flexible sensing material is characterized by specifically comprising the following steps: preparing at least one polymer solution, pouring the polymer solution into at least one composite tank, performing water bath heating on the composite tank, unwinding a carbon nano tube fiber or carbon nano tube membrane from a winding roller, leading through a leading needle, and feeding into the composite tank for combination; after the combination, performing grouting treatment through the guide needle, guiding, feeding into a heating area for drying so as to cure the polymer on the surface and inside the carbon nano tube fiber or carbon nano tube membrane, thereby obtaining the humidity-sensitive switch flexible sensing material. The humidity-sensitive switch flexible sensing material can be wound on a wire shaft connected with a motor. The humidity-sensitive switch flexible sensing material has the advantages of being low in cost, good in flexibility, good in conductivity, fiber-like, capable of being embedded into a monitored environment to be in contact with the monitored environment in all directions, and the like.