The invention discloses a terahertz frequency band space power amplification device suitable for the amplification of high gain power of the terminal of a terahertz frequency band. A cascade structure of microwave amplification array unit chips is used for amplifying a space-fed microwave signal firstly so as to increase the input power of a terahertz frequency multiplier; then the frequency multiplying characteristic of terahertz frequency multiplying array chips is used for the frequency multiplying of received microwaves, so as to obtain the high-power output of terahertz signals effectively; the structure of array chips is adopted, multiple sub-units are integrated on single chip, the integrated circuit technology and the one-time processing molding are utilized to obtain highly consistent microwave amplifiers and terahertz frequency multipliers, so as to ensure the effectiveness of the power amplification device of the terahertz terminal.