Abstract: An inductor current estimation method for a DC-DC switching power supply using a voltage sampling module, a data conversion module, a switching signal counting module, an inductor voltage calculation module and a digital filter module, comprising: processing an input voltage and an output voltage by the voltage sampling module and the data conversion module to obtain a converted input voltage and a converted output voltage which have a same number of bits; comparing a node voltage with a reference voltage, and then obtaining a duty cycle by the switching signal counting module; and then, outputting an average voltage of two terminals of an inductor and a parasitic resistor by the inductor voltage calculation module, and finally, obtaining an estimated inductor current by the digital filter module.