To better understand how ice sheets respond to climate, we designed a new multi-frequency ice-penetrating radar system to investigate subsurface structures of ice sheets. The system is mounted on a single platform and handled by a single operator. Three radio frequencies, 30,60 and 179 MHz, were used. An underlying principle of these multi-frequency observations is that the lower frequencies are more sensitive to electrical conductivity changes, whereas the higher frequencies are more sensitive to dielectric permittivity fluctuations in the ice. The system is composed of three single-frequency pulse radars, a trigger-controller unit and a data-acquisition unit. The trigger controller is the key component of this system. It switches transmitters on at different timings to prevent mixing of signals among the three radars. The timing difference was set as 50 μs, which is equivalent to the two-way travel time for radio waves reflecting from 4250m below the surface. A field test was done along a 2000 km long traverse line in east Dronning Maud Land, Antarctica. The multi-frequency system successfully acquired data that are equivalent in quality to our earlier single-frequency measurements along the same traverse line. The details of the system and preliminary data are described.