In this paper, the diamond film's advantages and disadvantages as a particle detector are analyzed. The techniques of fabrication, the mechanism of the detector, the configurations of its electrodes, as well as the level of development, are introduced. Meanwhile, a diamond film particle detector has been successfully fabricated in our laboratory. The detector performance was tested by measuring the energy spectra of α-particles emitted from an 241Am source and the response to X-ray. The obstacles of realizing detectors with high performance are also pointed out.