A method and an apparatus for detecting capacitance of a filter capacitor of an inverter are provided, wherein each output terminal of the inverter is connected to one terminal of a first filter capacitor through an inductor, and the other terminals of all first filter capacitors are interconnected. The method includes: outputting a first voltage {dot over (U)}1i through an ith output terminal of the inverter, i=1, 2 . . . N, i≠j, 1≤j≤N, i and j are positive integers, and N is a total quantity of output terminals of the inverter; obtaining İik and determining a ratio of |İij| to |İik|, where İik is a current of an inductor connected to a kth output terminal when the ith output terminal outputs the first voltage {dot over (U)}1i, k=1, 2 . . . N, and k is a positive integer; and determining capacitance of a first filter capacitor connected to the jth output terminal based on İij, {dot over (U)}1i, and the ratio of |İij| to |İik|.