In this study, a metal-topological insulator-metal (MTM) structure terahertz photodetector was fabricated based on a two-dimensional topological insulator Bi₂Te₃ material using a micro-nano process. The responsivity of device reaches 2×10³ A/W at 0.02 THz, the noise equivalent power (NEP) is lower than 7.5×10^-15 W/Hz^1/2, and the detectivity D* is higher than 1.62 ×10¹¹ cm?Hz^1/2 /W; The responsivity is up to 281.6 A/W at 0.166 THz, NEP is lower than 5.18×10^-14 W/Hz^1/2, D* is higher than 2.2×10¹⁰ cm?Hz^1/2/W; The responsivity is up to 7.74 A/W at 0.332 THz, NEP is lower than1.75×10^-12 W/Hz^1/2, D* is higher than 6.7×10⁸ cm?Hz^1/2 /W; at the same time, the response time of device has 7~8 μs in the terahertz band. This work breaks through the inter-band transition of traditional photon detection, and realizes terahertz detectors with room temperature operation, high response rate, high speed response and high sensitivity.