Abstract: An appropriate type of hollow glass microspheres was selected aiming at dealing with the leakage caused by high pressure of drilling fluid and its impact on the performance of the drilling fluid. The performance of hollow glass microspheres was evaluated, and its impact on the performance of the drilling fluid was tested from the aspects of dispersion stability, density, rheology and fluid loss and so on. A low-density drilling fluid system was optimized through a series of experiment with hollow glass microspheres used as the reducing agent. The drilling fluid system was proved to be of good rheology and filtration properties, excellent dispersion stability. The new drilling fluid system was applied in the complex formation of Ruoergai and it turned out to be of good applicability as the formation leakage was effectively prevented.