A turbo transmission mechanism for brush cutter is disclosed to include a casing defining therein a lubricant storage chamber, a transmission shaft rotatably mounted in the casing and partially inserted into the lubricant storage chamber, a transmission gear set mounted in the lubricant storage chamber of the casing and including a first bevel gear and a second bevel gear coaxially mounted at the transmission shaft and meshed with the first bevel gear for enabling the transmission shaft to be rotated by the second bevel gear during rotation of the first bevel gear by a power source, and a turbo mounted in the lubricant storage chamber and rotatable with the transmission shaft to stir up the lubricant in the lubricant storage chamber, enhancing heat dissipation.