In order to solve the problem of complex design of broadband absorber, a polarization insensitive metamaterial THz broadband absorber with simple structure and excellent absorption performance is proposed. The absorber adopts symmetrical structure design, which is based on the three-layer structure of metal layer-medium layer-metal layer. Two circular metal sheets of different sizes are embedded in the medium layer to form a multilayer structure. Frequency domain finite element method (FEM) is used to analyze the broadband absorption rate, polarization sensitivity and incident angle of the absorber. The simulation results show that the absorber can achieve wide band absorption of 5.86~7 THz, and the absorption bandwidth is 1.14 THz. The absorption rate is more than 95% within the bandwidth, and it is not sensitive to the polarization of vertically incident electromagnetic wave. And it still maintains broadband absorption within a certain incidence angle. The absorber has a simple structure design and excellent performance, which has important application value in terahertz imaging and electromagnetic stealth fields.