The invention belongs to the technical field of environment science and resource utilization, and particularly discloses a novel efficient heavy metal adsorbent adopting corn leaves and reed leaves as raw materials, a preparing method thereof and applications of the adsorbent. A simple and effective modification method is adopted to prepare the adsorbent. An alkaline compound solution the mass percentage of which is 0.1-1.0% is adopted to separately treat the dried corn leaves and reed leaves, and the adsorbent is prepared under conditions such as a water bath. The adsorbent has characteristics of high adsorbability and a high adsorption rate. In addition, the raw materials are wide in source and cheap, energy is saved, waste is utilized and environment is protected. The adsorbent is a novel heavy metal adsorbent simple in operation and low in energy consumption.