To enhance the ability of slotted device used in coal mines, a method of re-designing and optimizing the structure of slotted device is proposed. The objective of the research is dual gradient nozzle which is installed on a 63 slotted device. Based on orthogonal experiments, the realizable k-ε turbulence model is established to simulate the output flow distribution of the dual gradient nozzle with different parameters. The results show that when the L1=6 mm, θ1=18°, θ2=35°, L=6 mm and d=2.5 mm, the axial velocity reaches its peak at 150 mm from the target and then drops slowly. Based on the simulations, experiments of ability of nozzles are made on 3DPIV in the laboratory. The results show that when the parameters are L1=6 mm, θ1=18°, θ2=35°, L=6 mm and d=2.5 mm, the average velocity of the output flow distribution has its maximum value and the velocity distribution is reasonable. The average velocity of the dual gradient nozzle at 150 mm from the target is 1.4 times of that of ordinary nozzles.