The invention discloses a power supply circuit and relates to the energy collection field. The circuit comprises a first NMOS tube, a second NMOS tube, a first resistor, a reset chip, and several energy storage capacitors. A power supply input end is connected to a drain electrode of the first NMOS tube. A grid electrode of the first NMOS tube is connected to the drain electrode of the second NMOStube. A source electrode of the second NMOS tube is grounded. The first resistor is connected between the drain electrode and the grid electrode of the first NMOS tube. The source electrode of the first NMOS tube is connected to a power supply output end and the input end of the reset chip. A grounding end of the reset chip is grounded. A reset output end of the reset chip is connected to the grid electrode of the second NMOS tube. When a voltage of the input end of the reset chip is greater than a threshold potential, the reset chip outputs a high-level signal. One end of each energy storagecapacitor is connected to the power supply output end, and the other end of each energy storage capacitor is grounded. The power supply circuit of the invention can collect space energy and convert into electrical energy through a switch circuit composed of the two NMOS tubes and the reset chip, and can provide a voltage stabilization protection function.