Up to now, there are many methods for temperature sensing such as thermo couples, thermistor, thermovision, and ultrasound techniques. These thermom eters generally detect temperature on a macro scale which cannot satisfy the remote and realtime thermography inte grated on micro-nano devices. [8,9] Lumi nescence thermography can achieve high spatial resolution and remote operation because of the lower diffraction limit and high transparency. [4,10,11] The most reported luminescence thermography are based on semiconductor films with tem peraturedependent luminescence such as perovskites. [4,12,13] However, these lumines cent semiconductor films cannot achieve vertical integration and will incur interfer ence on the performance of chips due to the semiconductor nature.2D insulated van der Waals (vdW) rare earth (RE) materials have both the layered structure and intriguing temperature dependent luminescence properties. [14,15] 2D vdW RE materials have no dangling bonds and large spe cific surface area, which can be beneficial for achieving a better thermal contact with the target and high sensitivity. [16,17] With layered structure and insulated properties, 2D vdW RE mate rials can be easily integrated on semiconductor chips vertically without dangling bonds, so that a highdensity integration can be realized. [18,19] Besides, 2D vdW RE materials have excellent luminescence properties especially for the extremely narrow and multiple emissions spanning ultraviolet, visible, and infrared regions, which are ideal for probing temperature. [20,21] Luminescent thermometers can be achieved by monitoring the single emission, luminescence lifetime, and polarization. [4,22] However, single emissionbased luminescent thermometers will be badly affected by local fluctuation such as the concentra tion, size, and geometry of luminescent materials. [23,24] Lumi nescent thermometers based on lifetime and polarization need more complex and expensive employment, which are also not convenient for data processing. [25] Therefore, luminescence thermometers are better to detect intensity of two discrimi nable emission peaks to achieve ratiometric sensors. [26,27] Ratio metric luminescence thermometry can avoid optoelectronic fluctuations from the excited laser sources and detectors due Remote and real-time thermography integrated on micro-nano devices vertically can promote the integration while estimating their operation, which is hitherto challenging. Here, the ratiometric luminescence thermography integrated on micro-nano devices vertically based on 2D van der Waals (vdW) rare earth (RE) material ErOCl is demonstrated. Ratiometric luminescence intensity varies linearly with temperature deriving from the thermal activation between two thermally coupled levels. Typically, this ratiometric micro-nano thermometer has a wide sensing range (300-700 K), high relative sensitivity (2.2% K −1 at 300 K), and high repeatability. With layered structure and insulated properties, 2D ErOCl can be easily integrated on the target chips vertically without...