Visible+1.54μm laser/longwave infrared dichroic beamsplitters, which separate the incident spectrum into visible light, laser and longwave infrared light, take an important role in multichannel imaging spectrum technique. The choice of substrates and coating materials was discussed. Then the coating design of reflecting the visible(400～800nm) and laser (1540nm) light while transmitting the longwave infrared(8～12μm) spectrum was analysed, and the beamsplitter was manufactured by e-gun evaporation.The measured reflectivity and transmittance of the corresponding channel are all above 94% and the dichroic beamsplitters has been used in practical optical system successfully.