An ultra-lightweight proppant (ULWP) was successfully prepared, which was synthesized from crosslinked PMMA microspheres filled with 22 vol % of natural pine bark powder. The ULWP has excellent performances, such as low density (1.024 g cm(-3)), high compressive strength that only slight deformation appeared after a crush test under 10000 psi for 5 min, and very high heat resistance that glass-transition temperature reached 149.89 degrees C. Therefore, such a composite material is worthy of an excellent candidate for making ULWP in petroleum and gas exploration.