Ammonium ion is among water pollutants that harms the environment, high ammonium ion loads can cause eutrophication of natural waterways, impact water quality and ecosystem structure. Recently, biochar has attracted much attention in wastewater treatment since it is a high adsorption efficiency, environmental-friendly, and low-cost adsorbent. The purpose of this study was to investigate the removal of ammonium ion from aqueous solution using bamboo biochar. The experiment was conducted in lab and designed completely randomized with six replications. Batch experiments were carried out to investigate the effects of various factors such as pH solution, adsorbent dosage, reaction time, and initial ammonium concentration on adsorption process. Freundlich and Langmuir models were used to describe the equilibrium isotherm data. The results demonstrated that pH solution, adsorbent dosage, reaction time and initial ammonium concentration all affected ammonium ion removal from aqueous solution. The optimum ammonium adsorption 2.49 mg g^-1 reached at pH 7, reaction time of 60 minutes and adsorbent dose of 1.5 g L^-1).