Image sticking is an important factor affecting the quality of liquid crystal display (LCD) panel. The improvement of poor image sticking has been a continuous research topic in LCD panel factory. The degree of image sticking is positively correlated with the content of impurity ions. In order to monitor the content of impurity ions in the LTPS(Low Temperature Poly-Silicon)-LCD cell, the measurement system of the LTPS-LCD panel test cell is systematically studied, and the stability and resolution of the measurement system are discussed. Firstly, the measurement system designes a new test cell for the LTPS technology panel, and then uses voltage holding residual (VHR) to evaluate the impurity ion content in the cell, and the measurement systems analysis (MSA) is used to evaluate the reliability. Finally, the resolution of the measurement system is tested by comparing the changes of VHR under different ultraviolet (UV) irradiation time and photo-alignment baking time. The experimental results show that the measurement system gage repeatability, reproducibility(Gage R&R%)is 10.77%, P/T is 26.93% <30%, distinguishable score is 13> 5, the measurement results are reliable and stable, and can effectively identify VHR differences. The test cell designed in this paper meets the requirements of the LTPS-LCD panel industry for impurity ion content monitoring, and provides important guidance for monitoring factory impurity ions in actual production.