A leveling and focusing servo control system is built to improve the focus accuracy of the differential parallel confocal laser direct writing system. To obtain a detection curve with high sensitivity, accuracy and stability, the cylindrical lens as an astigmatism element is combined with four-quadrant photodetector, and the differential astigmatism detection method and proportion integration differentiation(PID) feedback algorithms are employed to reduce errors caused by light source and external interference. By optimizing the optical parameters, the detection curve with high sensitivity and stability has been obtained, with a range of around 3 μm and a static focusing error of ±5.0 nm. The stretching of piezoelectric ceramic transducer(PZT) can be guaranteed within the depth of focus range in the dynamic mode. Nano-scale precision of the focal position can be achieved, and the tilt and pitch of lever adjuster approximate 0.01 mrad. Utilizing this system, gratings can be fabricated, and this system can provide reference for the fabrication of larger-size and higher-density gratings in the future.