Abstract: Microresonator-based soliton frequency comb (soliton microcomb) has the potential to revolutionize the field of time-frequency metrology and can be competitive solution for the synthesis of low-noise microwave signals. However, these photonic microwave oscillators are currently limited by the fundamental quantum noise and technical noise, which prevents further improvement in their performance. A low-noise soliton microwave oscillator that mitigates these limitations by virtue of the crystalline microresonator with both large mode area and ultrahigh quality factor is proposed in this paper. The soliton states are automatically initiated by the computer procedure and long-term stabilized using a Pound-Drever-Hall (PDH) locking technique under a 15 mW pump power. The absolute single-sideband phase noise of the 9.099 GHz microwave carrier is -85 dBc/Hz at 100 Hz, -111 dBc/Hz at 1 kHz and -126 dBc/Hz at 10 kHz. The frequency stability represented by the Allan deviation is measured as 4.6×10^-11 at 1s averaging time. Therefore, our results are comparable to the demonstrated ultralow-noise photonic microwave oscillators, and are also ready for the compact package by the diode laser pumping.