A method for perception and map construction of the unknown environmental information is described in this paper by analyzing and processing the data measured by laser range finder (LRF). The structure of the laser range finder, the structure of its returned measurement data, its working principle, and communication protocol are presented. The physical meaning of the data are studied and illustrated as well as its representation methods. The corresponding algorithm routine and the GUI interface program are introduced. Experiments are conducted to verify the range finding accuracy of the sensor and the data visualization method is also introduced. Results indicate that the proposed method is sufficiently valid and can satisfy the desired requirements.