Infrared photodetector is an important technology for both civilian and military applications. However, conventional commercial detectors generally require complex designs, expensive devices and cumbersome procedures. In this work, monoclinic phase VO2 (M1) nanorods (NRs) with metal-insulator transition properties were synthesized through a low-temperature hydrothermal reaction and subsequent annealing. The evolution of vibrational modes of VO2 (M1) NRs have been observed using Raman and IR spectroscopies during the structural phase transition. In addition, a high-sensitivity infrared photodetector based on a network of the VO2 (Ml) NRs was fabricated with a low-cost method, and the electron transfer processes in nanorod (NR) networks has been discussed. The device exhibited high photosensitivity, excellent stability, and reproducibility in atmospheric condition at room temperature.