A new resonant-type composite right/left-handed transmission line (CRLH TL) is proposed based on the combination of a complementary triangle split ring resonator pair (CTSRRP) etched on the ground plane and a series gap embedded in the conductor strip of a microstrip line. The CTSRRP, which is composed of two identical complementary triangle split ring resonators (CTSRR) with back-to-back splits, demonstrates negative permittivity. Besides, a center branch is added to the middle of each triangle split ring to divide it into two parts. In virtue of this, two current paths of different length are formed which primely improve the multi-band characteristic of the transmission line (TL). The equivalent capacitor-inductor circuit model is put forward to analyze the TL. The S parameters are derived from electromagnetic full-wave simulation through simulation engine Ansoft HFSS13. Then the dispersion curve of the proposed structure is calculated based on S parameters to attest the left-handed characteristics. Two left-handed bands and two right-handed bands are observed from the dispersion curve. To demonstrate the applicability of the new type TL, a tri-band patch antenna of C band is designed and fabricated. Good agreement between simulated and measured return loss is obtained. Mea- sured results present that three available bands centered at 4.45 GHz, 5.55 GHz and 7.35 GHz respectively are acquired. Peak gain of more than 7 dB and invariable radiation characteristics can be observed from the simulated radiation patterns. And the cross polarization in working bands is less than −15 dB with the minimal touching bottom of −55 dB.