In order to improve the sealing performance of the conventional rubber of the packer used in the oilfield slicing process, especially in the well completion technology of unconventional oil and gas, and make the contact pressure more uniform, several shaped rubbers were designed by opening different size circular grooves at the side of the rubber contacted with center pipe. The finite element model of packer rubber was established based on nonlinear finite element method and using ANSYS finite element software, the sealing performances of the conventional rubbers and the shaped rubbers were compared, and the impact of circular groove radius on packer sealing performance was investigated. Results show that, compared with the conventional rubber, the shaped rubbers have higher maximum contact pressure and more uniform contact pressure distribution, so they have better sealing performance. Within a certain range, the circular groove radius has less influence on the contact pressure. The circular groove radius should be determined according to the actual situation for too large circular groove radius could reduce the sealing performance of packer.