Previously, the PtSe2 has been proved to absorb light in the infrared band, but most of devices based on PtSe2 were reported in visible light applications while few of them applied in near-infrared. In the visible band, the silicon may absorb most of the light wave, and the device does not make full use of the absorption characteristics of the PtSe2. In our work, we form heterojunction by growing PtSe2 film directly on silicon substrates, the PtSe2 heterojunction has a wide response band. Zero-bias photoresponse in the heterojunctions is observed under broadband laser illumination of wavelengths from 635 to 2700 nm. The devices exhibit excellent performance, specifically, the responsivity is as high as 17.8 mAW−1 at 1550 nm, the Ilight/Idark ratio, specific detectivity, and response speed are 9.2 × 102, 2.38 × 109 Jones and 6/9 μs at room-temperature, respectively. The same device also responds to 635 nm wavelength, and its responsivity, specific detectivity and the Ilight/Idark ratio are 202 mAW−1, 4.39 × 1012 Jones and 1.31 × 105, respectively. Furthermore, it still observes an evident response at 2700 nm wave band. With the wide-band and fast response, the PtSe2/Si heterojunction has potential possibilities in the field of infrared and even mid-infrared photoelectric detection in the future.