With the development of semiconductor manufacturing to 1x nm technological node, the measurement accuracy of the focusing and leveling system is down to several tens of nanometers. In the range of nanoscale, integrated circuit (IC) process plays an important impact on the measurement accuracy of the focusing and leveling system. A kind of focusing and leveling measurement technology based on optical triangulation and moiré fringes method is proposed. Two sets of moiré fringes with π phase difference are imaged onto two detectors using the spatial splitting system. The height of wafer is calculated by normalized differential method. The sensitivity of the system on the IC process, especially on the light intensity fluctuations is reduced. Experimental results show that the measurement repeatability of the system is 8 nm (3σ) and the linear accuracy is 18 nm (3σ). When the light intensity fluctuates 90%, the linear accuracy changes 15 nm (3σ). When the light intensity fluctuates 65%, the linear accuracy changes less than 1 nm (3σ).