The focusing and leveling system is mainly realized by the measurement principle of optical triangulation. Linear charge coupled device (CCD) has the characteristics of high frame rate and high resolution, which is suitable for high-speed and high-precision triangulation measurement. A focusing and leveling project requires a linear array CCD with 2048 effective pixels and a line readout frequency of 5 kHz. For this reason, it is proposed to overclock the S11156-2048 linear array detector with a maximum rated readout frequency of 10 MHz to 12.5 MHz. The read-out drive is designed to meet the requirements of the system line read-out frequency. First, the feasibility of overclocking readout is verified theoretically. Then, the design of power supply, timing drive and analog front end is studied in detail. Finally, the photoelectric performance of the linear CCD imaging system is compared by using an integrating sphere light source at 6.0 MHz rated frequency and 12.5 MHz overfrequency. The experimental results show that the S11156-2048 detector adopts 12.5 MHz over-frequency readout design with no significant degradation in its optical and electrical performance, the signal-to-noise ratio is 54.22 dB, and the charge transfer efficiency is 0.999974, which meets the imaging performance requirements of the focusing and leveling system.