Animal manures (cow dung,pig manure) and cornstraw were used to investigate the effects of different temperatures(200,300,400 and 500℃) and different amount of straw (20%,40%,60%,80%) on yields and physicochemical properties of biochar produced in a closed lowoxygen reactor using pyrolysis process. The results showed that biochar yields,volatile content decreased gradually as pyrolysis temperature increased,while ash content,pH and total content of P,K and nutrient contents increased,N content first increased and then decreased. The pore characteristics of cow dung biochar were best at 400℃,while the pore characteristics of pig manure were poor. Adding straw improved pH of biochar and regulated nutrient content. Compared with pig manure biochar,cow dung biochar had better carbon yield,pH and pore characteristics. The nutrient content of cow dung was less than that of pig manure. Cow manure and straw mixed biochar is more suitable for using its pore characteristics as adsorbent and so on. Pig manure and straw mixed biochar is more suitable for using its nutrient characteristics as phosphate fertilizer production auxiliary or soil conditioner. The influence of mixed pyrolysis on the charcoal characteristics needs to be further studied.