A matched-line power divider with ultra-wide operational bandwidth using Collin taper was presented in this article. The effect on the lowest operational frequency caused by the length of Collin taper was simulated by MATLAB and discussed, the effect on insertion loss and isolation caused by resistivity and length of resistive film was simulated by HFSS and discussed, also. Such power dividers are appropriate for wideband instruments and measurement systems. One design example with operational bandwidth from 1 GHz to 40 GHz was simulated by HFSS, fabricated and measured. The measurement results were shown that the maximum additional insertion loss was 2.2 dB at 40GHz, the isolation among all operational bandwidth was better than 20 dB and better than 30 dB from 3-40 GHz, the return loss was better than 18 dB among all operational bandwidth. The volume of this power divider was 100×30×14 mm 3 .