The objective of the present study was to study the changes in compost particle and its relationship with other physicochemical process during aerobic composting employing 5%, 10%, 20% or 0% biochar. Changes of physicochemical and biological parameters and gases emissions indicated that appropriate biochar addition improved both degradation rate and final degree of the organic matter and simultaneously reduced CO2, CH4, N2O and NH3 emissions. Beneficial properties like stability and high porosity of biochar could optimize composting environment, accelerate the process of composting and facilitate microbial growth during the thermophilic composting stage, with increases of 1.3 x 10(10) to 1.5 x 10(11) cfu/g. Analysis of microstructure characterization of the changes in compost particle indicated that biochar amended contributed to better degradation of compost particle with smaller sizes and a higher degree of looseness. Ultimately, 10% biochar addition optimized organic matter degradation, while reducing ammonia and greenhouse gas emissions and costs. (C) 2017 Published by Elsevier Ltd.