A novel structure composite-channel Al0.3Ga0.7N/Al0.0 Ga0.95N/GaN HEMT (CC-HEMT) microwave monolithic integrated circuit voltage-controlled oscillator (VCO) was designed, fabricated and characterized. The CC-HEMT has 1 μm × 100 μm gate. The inter-digitated metal-semiconductor-metal (MSM) varactor is used to tune the frequency of VCO. The polyimide dielectric layer is inserted between the major metal traces and GaN buffer to improve Q factor of spiral inductors.The VCO exhibits frequency range between 7.04 ～ 7.29GHz with varactor voltage from 5.5V to 8.5V and average output power of 10dBm and average efficiency of 10.4% at bias gate of -3V and bias drain of 6V. The measured phase noise is-86.25dBc/Hz and -108dBc/Hz at offset frequency of 100 kHz and 1 MHz at varactor voltage (Vtune) of 6.7V. This is almost average phase noise in the range of tuning frequency. To our knowledge, this is the best reported phase noise for GaN monolithic GaN HEMT VCO.