Reflective fiber optic sensor has always played an important role in the sensor field.Many scholars on the reflective optical fiber sensor research,mos tly assumes that the incident light into perpendicular to the reflecting surface,in order to explore on the premise of incident light and the reflector into acute Angle,light intensity modulation ch aracteristics,various influencing factors in this paper the incident light and the reflective surface of the fiber is under the condition of oblique incidence,assumes that the light intensity in line with th e ideal uniform distribution,reflective surface for the ideal smooth reflecting surface,light intensity of each link loss rate constant,light emphasis on system model is obtained by theoretical an alysis,using the method of control variables,the corresponding results of characteristic curve d rawing through Matlab simulation,analysis of simulation results,Get transmitting optical fibe r core diameter, spacing between receiving optical fiber core,optical fiber,numerical aperture, fiber optic Angle and other parameters on emphasis on the law of the system,the conclusion shows that proper adjust various parameters can effectively improve the sensitivity of the sensor and the measuring range, according to the sensitivity of the height and width of the measurement range,c an be applied in different measuring objects,for oblique incidence of reflective fiber optic sen sors to provide theoretical basis for the physical design.