A single-point-probe-based slope profiler is a common measurement scheme for the measurement of freeform optical surfaces, which has been a challenging research direction. Efficiency is a key issue in two-dimensional scanning-based measurement. This study establishes a measurement system simulation model and reveals that the height reconstruction accuracy of different reconstruction algorithms is primarily correlated with the sampling density. The spatial resolution calibrated of the slope measurement device is also identified to be an essential part of the strategy. Based on a kind of slope profiler, this paper applies variable sampling intervals for different spatial frequency characteristics of the surface under test (SUT). The result shows that the reconstruction accuracy can be controlled by selecting sampling parameters and calibrating the slope measurement device. For objects with different spatial characteristics, targeted optimization of the measurement scheme can be achieved. This strategy also has a certain universality for general scanning slope measurement and height reconstruction, providing a reference for device selection and sampling settings for different spatial frequency measurement requirements.