In this paper, an infrared thermal detector based on a metamaterials structure is proposed. It achieved the detection of radiation by utilizing the local field enhancement effect of optical metamaterials and the temperature-sensitive properties of pyroelectric materials. A finite element analysis method was utilized to analyze the infrared absorption characteristics and electromagnetic field properties of the metamaterial absorber, as well as to analyze the thermal properties of the coupled structure of the metamaterial absorber with a pyroelectric material (LiTaO3). The results show that the designed metamaterial absorber can modulate the peak wavelength in the range of 3 to 15 μm (mainly covering the atmospheric window (8~14 μm)), with an absorbance rate of 99.9% and a bandwidth of 0.2 to 1 μm. When the detector size is 23 μm×23 μm, the steady-state temperature increase of the detector is 0.311 K, which is about 21 times higher compared to similar studies. Improved infrared heat detector has significant temperature response, and it is applicable to thermal imaging and sensing in uncooled mid-infrared and far-infrared wavelengths at the large-scale image element level.