Aiming at the requirements of terahertz radiation power compatibility test for free space and waveguide transmission, a multi-function terahertz pyroelectric detector with a photosensitive surface diameter of 10 mm is studied. By means of the finite element analysis and the thermoelectric coupling simulation design, the model of terahertz pyroelectric detector, whose sensitive element is composed of the LiTaO3 wafer with the thickness of 100 m and the carbon nanotubes absorption layer, is established; the process problem of using the large wafer and multi-array method to manufacture the sensitive components of LiTaO3-based terahertz pyroelectric detector is solved, and the development of terahertz pyroelectric detector is completed by using key processes such as optimized precise thinning, polishing and Lift-Off. Under the setting conditions, the responsivity of the terahertz pyroelectric detector is 371.8 V/W, and the noise equivalent power is 0.34 nW/Hz1/2. The experimental results show that the designed and manufactured terahertz pyroelectric detector has high integration, good responsivity and low noise equivalent power, which can effectively solve the power test problem of terahertz beams with large light spots.