The invention discloses a switching power supply chip and a switching power supply circuit comprising the same. The switching power supply chip comprises a controller and a power switch; the controller comprises a high-voltage diode, a first resistor and a second resistor, a first comparator and a second comparator, a first switching tube and a second switching tube, and a control signal generation module; in the starting process of the switching power supply chip, a linear voltage received by a linear voltage detection pin from the external supplies a starting current for the switching power supply chip through the first resistor and the high-voltage diode; in the working process of the switching power supply chip, the first comparator, by making comparison between a linear voltage sampling value of a connecting node between the first resistor and the second resistor, and a first reference voltage, generates a linear voltage overvoltage detection signal; the second comparator, by making comparison between a linear voltage sampling value and a second reference voltage, generates a linear voltage undervoltage detection signal; and the control signal generation module generates signals for controlling the power switches to be switched on and switched off based on the linear voltage overvoltage detection signal and the linear voltage undervoltage detection signal.