A pixel circuit and a driving method thereof, and a display device. The pixel circuit includes a pixel unit and a bias-voltage regulating circuit. The pixel unit includes: a driving circuit configured to generate a driving current according to a control voltage at a light-emitting stage; a light-emitting control circuit configured to output the driving current to drive the light-emitting device to emit light at the light-emitting stage; a data writing circuit configured to write a data voltage into the driving circuit; a reset circuit configured to reset the driving circuit under control of a reset voltage, and to reset the light-emitting device under control of a gate line; and a bias-voltage regulating circuit configured to, before the data writing circuit writes the data voltage into the driving circuit, perform bias voltage regulation on the driving circuit to control the pixel unit to be in a bias voltage state.