Multi-zone or multi-seam commingled production in CBM reservoir is an attractive option for extending and/or increasing existing gas production. To solve the problem of interlayer interference during commingled production, with varying permeability and pressure difference between coal seams, numerical simulations are carried out using a gray lattice Boltzmann method. Under different conditions of multi-seam commingled production, the pressure and velocity distributions are obtained. Then, the effects of permeability and pressure contrast on multi-seam commingled production are investigated. The results show that under the condition of commingled production with different permeability contrast, a greater permeability contrast will lead to a greater difference in gas production of each seam. And the smaller the reservoir permeability is, the faster the decrease of reservoir pressure near the wellbore is. For commingled production with different pressure contrast, the interlayer interference coefficient increases linearly with the increase of the pressure contrast. The interference degree of low pressure seam is far greater than that of high pressure seam. A lower reservoir permeability will lead to a greater interference coefficient. The research results provide a basis for revealing the interlayer interference mechanism, production dynamic analysis and production system optimization in multi-seam commingled production.