Laser triangular displacement sensor (LTDS) is widely used in various high-precision measurement scenarios, but the accuracy of the sensor will be distinctly reduced in a working environment with extreme temperature. The mechanical structure, optical crystal and illuminant of the sensor will be distorted or drifted due to the impact of temperature change. This paper focuses on the spatial drift characteristics of illuminant on the measured surface with temperature change. The self-developed LTDS prototype is used to conduct the temperature-rising experiment of the "illuminant - collimated lens" system, and the centroid drift of the spot formed by the illuminant under two different power supply currents (16mA and 24mA) is recorded. The experimental results show that the centroid of laser spot appears clustering phenomenon in the process of heating. After filtering the noise generated by clustering phenomenon, the drift of the centroid of laser spot in the spatial plane presents a linear directional law, and the drift distance presents a quadratic function relationship with the change of temperature. In addition, the error evaluation model is used to calculate the actual measurement error of the sensor caused by the centroid drift of the spot. The measurement error of the sensor is quadratic function with the change of temperature. Comparing the results of heating experiment under 16 mA and 24 mA power supply, choosing appropriate power supply current (24 mA) can effectively suppress clustering phenomenon and improve the stability of illuminant.