In this study, biochar produced by anaerobic combustion of wheat straw and corn straw in Henan Province at 300 ℃, 500 ℃ and 700 ℃ was used. The chemical properties of wheat biochar and corn biochar, such as pH and infrared spectra, were studied with the increase of temperature. The chemical properties of wheat and corn biochars were compared based on the related literatures.It was found that the pH of biochar from wheat straw and corn straw combustion increased with the increase of temperature. Through the analysis of infrared spectra, it was found that the pH change of the two biochars may be related to the content of functional groups in the biochars themselves. With the increase of temperature, the spectra showed that the functional groups of the two biochars, such as hydroxyl and carboxyl,The main reason is that the chemical bonds of the above functional groups are broken with the increase of temperature. Resulting in a decrease in the number of acidic functional groups and an increase in the alkalinity of the biochar.