The invention discloses a low temperature sintered microwave dielectric ceramic Ca4Bi6O13 and a preparation method thereof. The chemical formula of the low temperature sintered microwave dielectric ceramic is Ca4Bi6O13. The preparation method comprises the following steps: (1) weighing and mixing original powder, with purity above 99.9%, of CaCO3 and Bi2O3 according to the chemical formula Ca4Bi6O13; (2) carrying out wet ball milling on the raw material mixture obtained in the step (1) for 12 hours and presintering the powder in an atmosphere at 700 DEG C for 6 hours after drying the powder, wherein the solvent is distilled water; (3) adding a binder to the powder prepared in the step (2) and then granulating the mixture, then carrying out compression forming and finally sintering the product in an atmosphere at 750-780 DEG C for 4 hours, wherein a polyvinyl alcohol solution with mass concentration of 5% is adopted as the binder and the dosage of the binder is 3% of the total mass of the powder. The prepared ceramic is well sintered at 750-780 DEG C, has dielectric constant of 15-16 and quality factor (Qf) as high as 84000-95000GHz, has low temperature coefficient of resonance frequency and has great application value in industry.