In view of the current research status of terahertz detectors, the advantages and disadvantages of existing terahertz detectors are analyzed, and the pyroelectric materials and absorbent materials of pyroelectric terahertz detectors are studied. A new design and fabrication method of terahertz detectors based on PMNT chips is proposed. Using PMNT wafer as pyroelectric material, carbon nanotubes as absorption material, using precision thinning polishing technology and sputtering electrode technology, the design and manufacture of a new pyroelectric terahertz detector are completed. And using the detector designed a terahertz power meter, after testing, the power meter in 0.1~30 THz wide band, 0.5~100 mW high power dynamic range, the power measurement accuracy reached±10%, the comprehensive index reached the international advanced level of similar products, the application effect is good.