Biochar is regarded as an ideal adsorbent because of its low cost, high adsorption performance, large porosity and high carbon content, which can effectively adsorb organic pollutants in wastewater. The present study explores the modified pomelo peel based biochar used to remove methylene blue (MB) from the simulated wastewater and its adsorption mechanism. The calcinated biochar prepared by pomelo peel under the three temperatures (450ºC, 500ºC and 550ºC) was characterized using SEM, FI-IR, XRD, N₂ adsorption and TGA. The removal conditions were optimized by response surface methodology (RSM) and artificial neural network-particle swarm optimization (ANN-PSO). The results showed that the bulk structure and surface rougher of the biochar increase with the rising of calcination temperature. The prepared materials contained a large number of active functional groups such as lignin, cellulose and hemicellulose. The specific surface area of the calcinated materials at 450ºC, 500ºC and 550ºC is 2.511, 3.353 and 4.344 m²/g, respectively, which were belong to mesoporous materials (2-50 nm). ANN-PSO was more suitable than that of RSM to optimize the removal conditions of MB using the prepared materials. The maximum removal efficiency of MB was reached at 89.72% under temperature = 34.63ºC, reaction time = 80.00 min, initial MB concentration = 169.73 mg/L and initial pH = 7. The actual removal efficiency of verification experiment was 87.96%, and the absolute error was 1.76%. The process of MB adsorbed onto the prepared biochar was well accordant with the pseudo second-order kinetic and Langmuir models. The adsorption process of MB by the biochar was a spontaneous, endothermic and entropy-driven. In summary, it is thus indicated that the modified pomelo peel based biochar can be regenerated within fourth cycle and have application prospect as a useful adsorbent for water treatment.