The invention belongs to the technical field of water treatment, and relates to a method for removing sulfamethoxazole in a water body by using modified bamboo charcoal, which comprises the following steps: sequentially carrying out pulverization, ultrasonic treatment, impregnation-process iron oxide loading and freeze-drying on bamboo charcoal to obtain modified bamboo charcoal, and adsorbing and removing sulfamethoxazole in the water body by using the modified bamboo charcoal as a filler or adsorbent. Compared with the prior art, the ultrasonic/impregnation-process iron oxide loading greatly enhances the antibiotic removal capacity of the bamboo charcoal. The adsorbent is high in adsorbability and easy to prepare; and the method is convenient to operate and low in price. The method is applicable to a sulfamethoxazole wastewater treatment technique, and has favorable economic and environmental benefits.