In this paper,we design and fabricate a novel three-dimensional passive-micro-mixer by using Polymethyl methacrylate( PMMA). The mixer is fabricated by using ultra-precision engraving machine and bonded by an organic solvent fumigation bonding method. The mixer combines two fluid streams into a mixing chamber integrated with T-shaped pre-mixing and six tortuous shaped mixing elements. We have employed three-dimensional numerical simulations to evaluate the mixing efficiency. The simulation results indicate,under inlet fluid pressure p = 10( Pa), compared to the planar serpentine mixer and tortuous mixer,the concentration fluctuation range at the outlet diagonal reduce to 48% and 71. 6% respectively. And the mixing concentration variances also show that the mixing efficiency has a significant increase. We characterize the device by using visualization microscope,and the results are consistent with the simulation data. The device demonstrates the promising capabilities for micro total analysis system integration. In this paper, we design and fabricate a novel three-dimensional passive-micro-mixer by using Polymethyl methacrylate (PMMA). The mixer is fabricated by using ultra-precision engraving machines and bonded by an organic solvent fumigation bonding method Two fluid streams into a mixing chamber integrated with T-shaped pre-mixing and six tortuous shaped mixing elements. We have employed three-dimensional numerical simulations to evaluate the mixing efficiency. The simulation results indicate that under inlet fluid pressure p = 10 (Pa ) compared to the planar serpentine mixer and tortuous mixer, the concentration fluctuation range at the outlet diagonal reduce to 48% and 71. 6% respectively. And the mixing concentration variances also show that the mixing efficiency has a significant increase. device by using visualization microscope, and the results are consistent with the simulation data. The device demonstrates the promising capabilities for micro total an alysis system integration.