In this paper, a novel design for triple-band microwave rectifier is proposed with compact size and high power conversion efficiency, where step-lines were employed to suppress triple-band second harmonics of for efficiency improvement, and triple-band operation was obtained by applying a cross-shape fundamental matching network for the first time. The notable point in this proposal compared to the published research is that the structures are optimized when the harmonics suppression network uses only two transmission lines connected in series, while the triple-band fundamental matching network only requires four transmission lines to realize. Furthermore, the parameters of these transmission lines are determined specifically by the closed-form equations built on transmission line theory. This proposed methodology was verified by a fabricated rectifier based on a voltage doubler configuration using Schottky diode BAT15-03W with the size of 9 cm2. The measurement results show that the peaks of power conversion efficiency are 81.48%, 79.4%, and 73.3% at 0.91 GHz, 2.41 GHz, and 5.61 GHz, respectively. Compared to other publications about triple-band microwave rectifiers, the rectifier designed with the proposed methodologies has superior power conversion efficiency and electrical size.