ing at the problem of repeated calibration in the traditional mobile screen deflectometry, a deflectometry measurement method of single-camera monitoring is proposed based on the principle of the phase measurement deflectometry. The two positions of a LCD screen were monitored by an auxiliary camera, and the position of the LCD screen relative to the main camera was determined by the PnP method and the coordinate system transformation. The incident light was determined by the absolute phase tracking of the homonymy phase points at two positions of the LCD screen for the same pixel. Accordingly, the normal line and gradient information were determined and the mirror surface was reconstructed accurately through the radial basis function interpolation. The two cameras with different fields of view were calibrated by the mirror calibration method. The calibration was implemented only once without the repetitive error. The results of the simulation and experiments verify the feasibility of the proposed method and show the method has a relatively high detection accuracy.