In this paper, a square symmetrical metamaterial terahertz multi-frequency absorber is designed, which can solve the problem of high frequency, multi-frequency, and high absorption rate of the absorber. The terahertz absorber is composed of a metal-dielectric-metal structure, the bottom layer is a metal film, the middle layer is a polycarbonate dielectric substrate, and the top layer is a square symmetrical metal resonance structure. The finite difference time domain method is used to simulate the transmission and reflection performance of the absorber. The finite-difference time-domain method is used to simulate the transmission and reflection performance of the absorber. Through calculation, five obvious resonant absorption peaks are obtained in the frequency range of 3-10 THz. The frequencies of the absorption peaks are 4.8 THz, 6.55 THz, 6.85 THz, 7.65 THz, and 7.88 THz, respectively. The absorption rates of these absorption peaks can reach 98.56%, 99%, 99.64%, 99%, and 90.39%, respectively. The characteristics of multi-frequency and high absorption rate are realized, and the absorber is insensitive to the incident angle. It can still maintain excellent absorption characteristics at large incident angles. The unit size of the absorber is 50 μm × 50 μm × 9.6 μm, which can be used in the fields of multi-function, multi-channel, multi-frequency communication, and plays a role in preventing electromagnetic pollution, eliminating electromagnetic interference, and improving weapon combat capability.