The invention discloses high-quality-factor temperature stable type ultralow dielectric constant microwave dielectric ceramic CaLi4Ge5O13 and a preparation method thereof. The method includes the steps that 1, CaCO3, Li2CO3 and GeO2 original powder with the purity being 99.9% and above are weighed and matched according to the composition of CaLi4Ge5O13; 2, the raw materials in step 1 are subjected to wetted ball grinding for 12 hours, the ball grinding medium is water, and the raw materials are presintered for 6 hours in air atmosphere at the temperature of 750 DEG C after being dried; 3, binder is added to powder obtained in step 2, pelleting is conducted, then pressing and forming are conducted, and finally sintering is conducted for 4 hours in air atmosphere at the temperature of 800-850 DEG C; a polyvinyl alcohol solution with the mass concentration being 5% is adopted for the binder, and the polyvinyl alcohol accounts for 3% the total mass of the powder. The ceramic prepared through the method is good in sintering performance at the temperature of 900 DEG C and below, the dielectric constant reaches 14.5-15.2, the quality factor Qf value is as high as 87000-126000 GHz, the temperature coefficient of resonance frequency is small, and the temperature stable type microwave dielectric ceramic CaLi4Ge5O13 has extremely high industrial application value.