The offshore platform is an important equipment for offshore operations and the seismic performance of offshore platforms has received extensive attention. An extended method of tuned mass damper (ETMD) control was proposed to improve the seismic performance of offshore platforms. The elastic damping was used to connect offshore platform and platform equipment, which is different from the rigid connection of traditional offshore platform equipment. The finite element model of offshore platform with ETMD system was simulated. Taking the low-order natural frequencies of offshore platforms as controlled frequencies, the seismic performance of offshore platforms under three typical seismic loads was compared and analyzed. The simulation results showed that under the action of three typical seismic waves, the vibration of jacket, lower deck, middle deck and upper deck of off- shore platform can be significantly suppressed, and the average reduction rate of vibration was more than 52.86%. The maximum vibration average reduction rate of offshore platform could reach up to 89.91% in the X direction, and the vibration reduction effect was the most obvious. The application of ETMD damping system can significantly improve the seismic performance of offshore platforms.