In order to realize the inner-hole-depth measurement and the profile of the bottom surface measurement of parts with holes, especially deep-hole parts, an inner hole measuring sensor with laser triangulation was designed. The applied designs such as mechanical structure and optical designs, system imaging characteristics, and the analysis and evaluation of optical aberration based on the software Zemax were investigated. First of all, by using focusing lens, the laser light is focused to the surface to be measured, and flare is small enough. Then, put the required scattering light limit in a narrow range using the trapezoid prism total reflection characteristics. Finally, an imaging lens is used to make light foculize on CCD target surface. According to the geometric relation between the flare on CCD and hole depth, the depth of the hole and the profile of the bottom surface was calculated. Experimental results indicated that the measurement precision can reach 1 μm, and the design of using trapezoidal prism can well solve the problem of physical space limited as measuring inner hole. The combination with the principle of laser triangulation technique makes the system satisfy the requirements of simple structure, stabilization, higher precision and rapid speed.