The new generation of detection equipment urgently requires high-sensitivity detectors. Traditional silicon-based detectors cannot meet the requirements for sensitivity and channel size. Diamondene has excellent performance such as high carrier mobility and wide band gap. Its excellent electronic characteristics are expected to effectively improve the sensitivity of the detector and provide a new way for developing the next generation of detectors. However, the detection mechanism based on diamondene is still unclear. Based on the above problems, the analytical model and mechanism of the transistor channel are first studied. By analyzing the relationship between the surface potential distribution of the current channel and the effective channel size in the working state and the sensitive characteristics of the two-dimensional material electrons of the channel, a theoretical model of the transistor detector is constructed based on the electronic characteristics of the channel material, and the working characteristics of the detector are investigated. The finite element simulation of the working mechanism, potential and electron distribution of the transistor detector is carried out. The simulation results show that the mobility level of the diamondene-based detector is 2.5 times that of the traditional silicon-based detector, which theoretically verifies the hypersensitive detection characteristics of the diamondene-based detector. This study is of great significance in designing and applying a new generation of carbon-based ultra-sensitive detection devices.