In the field of high temperature sensing applications, Silicon carbide (SiC) is a superior material due to its excellent mechanical, thermal and chemical properties. Laser triangulation is a technology of non-contact, rapidity, and high accuracy. Its characteristic of non-contact can realize the high temperature non-resistance components’ isolation from the high temperature components of the sensor effectively, so as to achieve measurement under high temperature. Meanwhile, its measurement accuracy can be further improved effectively by using the principle of lens imaging of magnification and constant focus, combining with the high-resolution photodetector. This paper first applied it to the measurement of pressure under high temperature, and proposed a laser-type high temperature pressure sensor using SiC diaphragm as the pressure-sensitive diaphragm. The sensor measured the center deflection of the circular SiC diaphragm caused by pressure and temperature using the laser triangulation, then created the corresponding relationship between the pressure, temperature and deflection according to the thermoelasticity theory. The paper first established the mathematical model of the high accuracy laser triangulation. Afterward did the thermomechanical finite element analysis of the SiC diaphragm using ANSYS. The research and analysis demonstrate that this technical scheme of measurement of pressure under high temperature is effective and feasible, and provide a forceful and important basis for the design and realization of the sensor.