The invention discloses a transition structure from a non-uniform microstrip line to a strip line. The structure comprises metal layers and dielectric layers, wherein the number of the metal layers is N; N is greater than or equal to 4; the N metal layers are stacked in sequence; the number of the dielectric layers is N-1; each dielectric layer is arranged between every two adjacent metal layers; the structure further comprises a non-uniform input microstrip line, a non-uniform output microstrip line, a strip line, a circular groove and a signal blind hole; the non-uniform input microstrip line and the non-uniform output microstrip line are arranged on the first metal layer; when the number N of the metal layers is equal to 4, the strip line is arranged on the third metal layer, and the circular groove is formed in the second metal layer; when the number of the metal layers is greater than 4, the strip line is arranged in any metal layer from the third metal layer to the N-1 metal layer, and the circular groove is formed in any metal layer from the second metal layer to the metal layer in which the strip line is arranged; the vertical projection of the signal blind hole is positioned in the vertical projection of the circular groove; the signal blind hole is used for connecting the strip line with a non-uniform input microstrip line and a non-uniform output microstrip line. The structure can be applied to non-uniform microstrip line structures.