Carbon microspheres (CMSs) were obtained via a simple hydrothermal method using fructose and xylose as the carbon sources, PEO106PPO70PEO106 (F127) and poly(vinylpyrrolidone) (PVP) as the assistant agent. Carbon source and assistant agent have important effects on the morphologies of the products. Highly dispersed CMSs synthesized with fructose and F127 had an average size of 694 nm and smooth surfaces, and xylose-based CMSs had an average size of 620 nm. However, the carbon layer regularity of fructose-based CMSs is higher. In addition, there were almost no spheres with smooth surface in the products when adding PVP.