To study the triaxial compressive performance evolution law of recycled aggregate concrete (RAC) with a fully replacement rate after high temperature, 20 RAC specimens with a fully replacement rate were designed and fabricated, and triaxial compressive experiments were conducted on them after different high temperatures. The research results show that all the uniaxial stress-strain curves of specimens after different high temperatures have a significant decrease segment. The curves of specimens gradually become plump with the increase of lateral stress. When the lateral stress exceeds 10 MPa, the curve no longer has a significant decrease segment. The triaxial compressive strength and peak strain of specimens present a linear increasing trend with the increase of lateral stress. After being subjected to a high temperature of 600 ℃, the triaxial compressive strength of the specimens shows a significant decrease. With the increase in temperature, the energy dissipation performance of specimens shows a trend of first increasing and then decreasing. The existence of lateral stress can effectively suppress the internal damage development of specimens, improve their energy dissipation performance, and reduce the influence of high temperature on their triaxial compressive strength and peak strain. Based on the experimental data, a universal calculation formula for the triaxial compressive strength and peak strain of RAC with a fully replacement rate under different high temperatures was constructed, and the theoretical value has a good agreement with the experimental results.