The dual-material micro-cantilever structure is adopted to realize a quantitative detection method for the micro-quantity liquid. The method is based on the temperature sensitivity of bi-material micro-cantilever. When the micro-quantity liquid analyte absorbs the light of the characteristic wavelength of the photothermal spectrum, it′s temperature changes, the cantilever will be bent accordingly, and the amount of bending is measured with the optical lever method, so that the quantitative detection of the micro-quantity liquid is realized with the micro cantilever. In order to verify the applicability of measuring the micro-quantity liquid, the NaYF4 sample solution with a known light-heat absorption peak at 980 nm was used in the experiment, and multiple sets of 1 and 0. 5 μL solutions with known concentrations were taken for measurement. The relationship between the concentration and the measured voltage value was fitted by the least square method. The results show that the liquid concentration has a linear relationship with the measured voltage value, which is consistent with the theoretical analysis. And the linear correlation coefficients of the fitted curves of the sample solutions with the volume of 1 and 0. 5 μL are R1 = 0. 998 0, R2 = 0. 989 5, and the resolutions are 1. 25, 1. 40 mg / mL, respectively. Finally, multiple sets of different concentration solutions with a volume of 1 μL were tested, the errors of the concentration measurement results are all within 2 mg / mL, which indicates that the proposed method can effectively detect the concentration and can be used in the concentration detect of the volume determined micro-quantity liquid.