Application of tunable diode absorption spectruscopy(TDLAS) to power plant FG tail duct or extraction measurement could reflect the combustion condition to some extent. But it is not a direct and rapid method. To support the diagnose the combustion process more directly, this present paper designed a combust TDLAS sensor to measure the coal-fired power plant using a pair of H2O transitions near 1.3 μm. The temperature was measured during the whole starting process of the power plant, which is a support for developping non-intrusive in-situ measurement system and combustion controll.