Wildfires remarkably alter the quantity and quality of dissolved organic matter (DOM) that regulates postfire biogeochemical processes and environmental quality. However, it remains unclear how the heating-induced percent changes (%HIC) in DOM quantity and quality differ among soil types on a wide geographic scale. Here, we used dissolved organic carbon (DOC) quantification, absorption, and fluorescence spectroscopies, and Fourier transform ion cyclotron resonance mass spectrometry to investigate the variations in %HIC in DOM quantity and quality of Chinese soil reference materials after heating at 250 and 400 °C. Our results reveal that as soil pH increased, %HIC in DOC content increased, while %HIC in aromaticity-related indices of DOM decreased for both heating temperatures. Moreover, the %HIC in DOM biolability and contents of aliphatics increased with soil pH for 250 °C heating but remained relatively stable for 400 °C heating. Results suggest that compared to those in acidic soil-dominated forests, wildfires in alkaline soil-dominated forests may cause greater DOM content and biolability in soils, which may facilitate postfire microbial recovery. These findings deepen our understanding of the site-specific impacts of wildfires on DOM and the subsequent implications for biogeochemical cycling and environmental quality across different geographic regions.